diff --git a/src/application/controllers/backend.php b/src/application/controllers/backend.php
index 7f7fcb4c..2c494371 100644
--- a/src/application/controllers/backend.php
+++ b/src/application/controllers/backend.php
@@ -42,7 +42,7 @@ class Backend extends CI_Controller {
     }
     
     /**
-     * Display the backend customers page
+     * Display the backend customers page.
      * 
      * In this page the user can manage all the customer records of the system.
      */
@@ -65,10 +65,18 @@ class Backend extends CI_Controller {
         $this->load->view('backend/footer', $view);
     }
     
+    /**
+     * Displays the backend services page. 
+     * 
+     * Here the admin user will be able to organize and create the services 
+     * that the user will be able to book appointments in frontend. 
+     * 
+     * NOTICE: The services that each provider is able to service is managed 
+     * from the backend services page. 
+     */
     public function services() {
         // @task Require user to be logged in the application.
         
-        $this->load->model('providers_model');
         $this->load->model('customers_model');
         $this->load->model('services_model');
         $this->load->model('settings_model');
@@ -83,15 +91,44 @@ class Backend extends CI_Controller {
         $this->load->view('backend/footer', $view);
     }
     
-    public function providers() {
-        echo '<h1>Not implemented yet.</h1>';
+    /**
+     * Display the backend users page.
+     * 
+     * In this page the admin user will be able to manage the system users. 
+     * By this, we mean the provider, secretary and admin users. This is also
+     * the page where the admin defines which service can each provider provide.
+     */
+    public function users() {
+        // @task Require user to be logged in the application.
+        
+        $this->load->model('providers_model');
+        $this->load->model('secretaries_model');
+        $this->load->model('admins_model');
+        $this->load->model('services_model');
+        $this->load->model('settings_model');
+        
+        $view['base_url'] = $this->config->item('base_url');
+        $view['company_name'] = $this->settings_model->get_setting('company_name');
+        $view['providers'] = $this->providers_model->get_batch();
+        $view['secretaries'] = $this->secretaries_model->get_batch();
+        $view['admins'] = $this->admins_model->get_batch();
+        $view['services'] = $this->services_model->get_batch(); 
+        
+        $this->load->view('backend/header', $view);
+        $this->load->view('backend/users', $view);
+        $this->load->view('backend/footer', $view);
     }
     
+    /**
+     * Display the user/system settings.
+     * 
+     * This page will display the user settings (name, password etc). If current user is
+     * an administrator, then he will be able to make change to the current Easy!Appointment 
+     * installation (core settings like company name, book timeout etc). 
+     */
     public function settings() {
         echo '<h1>Not implemented yet.</h1>';
     }
-    
-    
 }
 
 /* End of file backend.php */
diff --git a/src/application/libraries/Unit_tests/drivers/Unit_tests_providers_model.php b/src/application/libraries/Unit_tests/drivers/Unit_tests_providers_model.php
index 64a4ff69..27b60f22 100644
--- a/src/application/libraries/Unit_tests/drivers/Unit_tests_providers_model.php
+++ b/src/application/libraries/Unit_tests/drivers/Unit_tests_providers_model.php
@@ -1,18 +1,18 @@
 <?php if ( ! defined('BASEPATH')) exit('No direct script access allowed'); 
 
 class Unit_tests_providers_model extends CI_Driver {
-    private $CI;
+    private $ci;
     private $provider_role_id;
     
     /**
      * Class Constructor
      */
     public function __construct() {
-        $this->CI =& get_instance();
-        $this->CI->load->library('Unit_test');
-        $this->CI->load->model('providers_model');
+        $this->ci =& get_instance();
+        $this->ci->load->library('Unit_test');
+        $this->ci->load->model('providers_model');
         
-        $this->provider_role_id = $this->CI->db->get_where('ea_roles', 
+        $this->provider_role_id = $this->ci->db->get_where('ea_roles', 
                 array('slug' => DB_SLUG_PROVIDER))->row()->id;
     }
     
@@ -34,6 +34,94 @@ class Unit_tests_providers_model extends CI_Driver {
     /////////////////////////////////////////////////////////////////////////
     // UNIT TESTS
     ///////////////////////////////////////////////////////////////////////// 
+    // TEST ADD METHOD
+    private function test_add_insert() {
+        $provider = array(
+            'first_name' => 'John',
+            'last_name' => 'Doe',
+            'mobile_number' => '000000',
+            'phone_number' => '111111',
+            'address' => 'Some Str',
+            'city' => 'Some City',
+            'state' => 'Some State',
+            'zip_code' => '12345',
+            'notes' => 'This is a test provider',
+            'id_roles' => $this->provider_role_id
+        );
+        
+        $provider['id'] = $this->ci->providers_model->add($provider);
+        $this->ci->unit->run($provider['id'], 'is_int', 'Check if add (insert) result is integer.');
+        
+        $db_record = $this->ci->db->get_where('ea_users', array('id' => $provider['id']))->row_array();
+        $this->ci->unit->run($provider, $db_record, 'Check if add(insert) has successfully '
+                . 'inserted a provider record.');
+        
+        $this->ci->db->delete('ea_users', array('id' => $provider['id']));
+    }
+    
+    private function test_add_update() {
+        
+    }
+    
+    private function test_add_with_invalid_data() {
+        
+    }
+    
+    // TEST EXISTS METHOD
+    private function test_exists_with_record_that_exists() {
+        
+    }
+    
+    private function test_exists_with_invalid_data() {
+        
+    }
+    
+    private function test_exists_with_record_that_does_not_exist() {
+        
+    }
+    
+    // TEST FIND RECORD ID METHOD
+    private function test_find_record_id() {
+        
+    }
+    
+    private function test_find_record_id_with_invalid_data() {
+        
+    }
+    
+    private function test_find_record_id_with_record_that_does_not_exist() {
+        
+    }
+    
+    // TEST VALIDATE RECORD METHOD
+    private function test_validate() {
+        
+    }
+    
+    private function test_validate_with_record_that_does_not_exist() {
+        
+    }
+    
+    private function test_validate_with_missing_required_fields() {
+        
+    }
+    
+    private function test_validate_with_invalid_email_address() {
+        
+    }
+    
+    // TEST DELETE RECORD METHOD
+    private function test_delete() {
+        
+    }
+    
+    private function test_delete_with_invalid_record_id() {
+        
+    }
+    
+    private function test_delete_with_record_that_does_not_exist() {
+        
+    }
     
     // TEST GET ROW METHOD      ---------------------------------------------
     private function test_get_row() {
@@ -48,25 +136,25 @@ class Unit_tests_providers_model extends CI_Driver {
             'zip_code' => '12345',
             'id_roles' => $this->provider_role_id
         );
-        $this->CI->db->insert('ea_users', $provider);
-        $provider['id'] = intval($this->CI->db->insert_id());
+        $this->ci->db->insert('ea_users', $provider);
+        $provider['id'] = intval($this->ci->db->insert_id());
         
         // Get the new customer record from db.
-        $no_model_data = $this->CI->db->get_where('ea_users', array('id' => $provider['id']))
+        $no_model_data = $this->ci->db->get_where('ea_users', array('id' => $provider['id']))
                 ->row_array();
-        $model_data = $this->CI->providers_model->get_row($provider['id']);
+        $model_data = $this->ci->providers_model->get_row($provider['id']);
         
         // Check that the row is the correct one.
-        $this->CI->unit->run($no_model_data, $model_data, 'Test get_row() method');
+        $this->ci->unit->run($no_model_data, $model_data, 'Test get_row() method');
         
         // Delete inserted customer record.
-        $this->CI->db->delete('ea_users', array('id' => $provider['id']));
+        $this->ci->db->delete('ea_users', array('id' => $provider['id']));
     }
     
     private function test_get_row_that_does_not_exist() {
         $random_record_id = 486868412;
-        $row_data = $this->CI->providers_model->get_row($random_record_id);
-        $this->CI->unit->run($row_data, NULL, 'Test get_row() with record id that does ' 
+        $row_data = $this->ci->providers_model->get_row($random_record_id);
+        $this->ci->unit->run($row_data, NULL, 'Test get_row() with record id that does ' 
                 . 'not exist in the database.');
     }
     
@@ -75,12 +163,12 @@ class Unit_tests_providers_model extends CI_Driver {
         
         $has_thrown_exception = FALSE;
         try {
-            $this->CI->providers_model->get_row($invalid_id);        
+            $this->ci->providers_model->get_row($invalid_id);        
         } catch (Exception $exc) {
             $has_thrown_exception = TRUE;
         }
         
-        $this->CI->unit->run($has_thrown_exception, TRUE, 'Test get_row() with wrong argument.');
+        $this->ci->unit->run($has_thrown_exception, TRUE, 'Test get_row() with wrong argument.');
     }
     
     // TEST GET VALUE METHOD    ---------------------------------------------
@@ -96,17 +184,17 @@ class Unit_tests_providers_model extends CI_Driver {
             'zip_code' => '12345',
             'id_roles' => $this->provider_role_id
         );
-        $this->CI->db->insert('ea_users', $provider);
-        $provider['id'] = intval($this->CI->db->insert_id());
+        $this->ci->db->insert('ea_users', $provider);
+        $provider['id'] = intval($this->ci->db->insert_id());
         
         // Get a specific value from the database.
-        $model_value = $this->CI->providers_model->get_value('email', $provider['id']);
+        $model_value = $this->ci->providers_model->get_value('email', $provider['id']);
         
         // Check if the value was correctly fetched from the database.
-        $this->CI->unit->run($model_value, $provider['email'], 'Test get_value() method.');
+        $this->ci->unit->run($model_value, $provider['email'], 'Test get_value() method.');
         
         // Delete inserted appointment record.
-        $this->CI->db->delete('ea_users', array('id' => $provider['id']));
+        $this->ci->db->delete('ea_users', array('id' => $provider['id']));
     }
     
     private function test_get_value_record_does_not_exist() {
@@ -115,12 +203,12 @@ class Unit_tests_providers_model extends CI_Driver {
         $has_thrown_exception = FALSE;
         
         try {
-            $this->CI->providers_model->get_value('email', $random_record_id);
+            $this->ci->providers_model->get_value('email', $random_record_id);
         } catch (Exception $exc) {
             $has_thrown_exception = TRUE;
         }
         
-        $this->CI->unit->run($has_thrown_exception, TRUE, 'Test get_value() with record id that '
+        $this->ci->unit->run($has_thrown_exception, TRUE, 'Test get_value() with record id that '
                 . 'does not exist.');
     }
     
@@ -136,35 +224,35 @@ class Unit_tests_providers_model extends CI_Driver {
             'zip_code' => '12345',
             'id_roles' => $this->provider_role_id
         );
-        $this->CI->db->insert('ea_users', $provider);
-        $provider['id'] = intval($this->CI->db->insert_id());
+        $this->ci->db->insert('ea_users', $provider);
+        $provider['id'] = intval($this->ci->db->insert_id());
         
         // Try to get record value with wrong field name.
         $wrong_field_name = 'THIS IS WRONG';
         $has_thrown_exception = FALSE;
         
         try {
-            $this->CI->providers_model->get_value($wrong_field_name, $provider['id']);
+            $this->ci->providers_model->get_value($wrong_field_name, $provider['id']);
         } catch (Exception $exc) {
             $has_thrown_exception = TRUE;
         }
         
-        $this->CI->unit->run($has_thrown_exception, TRUE, 'Test get_value() with record id that '
+        $this->ci->unit->run($has_thrown_exception, TRUE, 'Test get_value() with record id that '
                 . 'does not exist.');
         
         // Delete inserted appointment record.
-        $this->CI->db->delete('ea_users', array('id' => $provider['id']));
+        $this->ci->db->delete('ea_users', array('id' => $provider['id']));
     }
     
     // TEST GET BATCH METHOD    ---------------------------------------------
     private function test_get_batch() {
         // Get all the customer rows without using the model.
-        $db_data = $this->CI->db->get_where('ea_users', 
+        $db_data = $this->ci->db->get_where('ea_users', 
                 array('id_roles' => $this->provider_role_id))->result_array();
         // Get all the customer rows by using the model.
-        $model_data = $this->CI->providers_model->get_batch();
+        $model_data = $this->ci->providers_model->get_batch();
         // Check that the two arrays are the same.
-        $this->CI->unit->run($db_data, $model_data, 'Test get_batch() method.');
+        $this->ci->unit->run($db_data, $model_data, 'Test get_batch() method.');
     }
     
     private function test_get_batch_with_where_clause() {
@@ -179,21 +267,21 @@ class Unit_tests_providers_model extends CI_Driver {
             'zip_code' => '12345',
             'id_roles' => $this->provider_role_id
         );
-        $this->CI->db->insert('ea_users', $provider);
-        $provider['id'] = intval($this->CI->db->insert_id());
+        $this->ci->db->insert('ea_users', $provider);
+        $provider['id'] = intval($this->ci->db->insert_id());
         
         // Get data without using the model.
-        $no_model_data = $this->CI->db->get_where('ea_users', array('id' => $provider['id']))
+        $no_model_data = $this->ci->db->get_where('ea_users', array('id' => $provider['id']))
                 ->result_array();
         
         // Get data by using the model. 
-        $model_data = $this->CI->providers_model->get_batch(array('id' => $provider['id']));
+        $model_data = $this->ci->providers_model->get_batch(array('id' => $provider['id']));
         
         // Check that the data arrays are the same.
-        $this->CI->unit->run($no_model_data, $model_data, 'Test get_batch() with where clause.');
+        $this->ci->unit->run($no_model_data, $model_data, 'Test get_batch() with where clause.');
         
         // Delete inserted record from database.
-        $this->CI->db->delete('ea_users', array('id' => $provider['id']));
+        $this->ci->db->delete('ea_users', array('id' => $provider['id']));
     }
 
     private function unabled_test_get_batch_with_invalid_where_clause() {
diff --git a/src/application/models/admins_model.php b/src/application/models/admins_model.php
new file mode 100644
index 00000000..cc050f31
--- /dev/null
+++ b/src/application/models/admins_model.php
@@ -0,0 +1,55 @@
+<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed.'); 
+
+class Admins_Model extends CI_Model {
+    /**
+     * Class Constructor
+     */
+    public function __construct() {
+        parent::__construct();
+    }
+    
+    public function add($admin) {
+        
+    }
+    
+    public function exists($admin) {
+        
+    }
+    
+    public function insert($admin) {
+        
+    }   
+    
+    public function update($admin) {
+        
+    }
+    
+    public function find_record_id($admin) {
+        
+    }
+    
+    public function validate($admin) {
+        
+    }
+    
+    public function delete($admin) {
+        
+    }
+    
+    public function get_row($admin_id) {
+        
+    }
+    
+    public function get_value($field_name, $admin_id) {
+        
+    }
+    
+    public function get_batch($where_clause = '') {
+        
+    }
+    
+    
+}
+
+/* End of file admins_model.php */
+/* Location: ./application/models/admins_model.php */
\ No newline at end of file
diff --git a/src/application/models/customers_model.php b/src/application/models/customers_model.php
index a6bb0858..ae2c7a25 100644
--- a/src/application/models/customers_model.php
+++ b/src/application/models/customers_model.php
@@ -142,7 +142,7 @@ class Customers_Model extends CI_Model {
                 ->get();
         
         if ($result->num_rows() == 0) {
-            throw new Exception('Could not find appointment record id.');
+            throw new Exception('Could not find customer record id.');
         }
         
         return $result->row()->id;
@@ -192,25 +192,20 @@ class Customers_Model extends CI_Model {
     /**
      * Delete an existing customer record from the database.
      * 
-     * @expectedException InvalidArgumentException Raises when 
-     * the $customer_id is not an integer.
-     * 
-     * @param numeric $record_id The record id to be deleted.
+     * @param numeric $customer_id The record id to be deleted.
      * @return bool Returns the delete operation result.
      */
-    public function delete($record_id) {
-        if (!is_numeric($record_id)) {
-            throw new Exception('Invalid argument type $customer_id : ' 
-                    . $record_id);
+    public function delete($customer_id) {
+        if (!is_numeric($customer_id)) {
+            throw new Exception('Invalid argument type $customer_id : ' . $customer_id);
         }
         
-        $num_rows = $this->db->get_where('ea_users', array('id' => $record_id))->num_rows();
+        $num_rows = $this->db->get_where('ea_users', array('id' => $customer_id))->num_rows();
         if ($num_rows == 0) {
             return FALSE;
         }
         
-        $this->db->where('id', $record_id);
-        return $this->db->delete('ea_users');
+        return $this->db->delete('ea_users', array('id' => $customer_id));
     }
     
     /**
diff --git a/src/application/models/providers_model.php b/src/application/models/providers_model.php
index 69647d3f..314142e1 100644
--- a/src/application/models/providers_model.php
+++ b/src/application/models/providers_model.php
@@ -8,6 +8,180 @@ class Providers_Model extends CI_Model {
         parent::__construct();
     }
     
+    /**
+     * Add (insert/update) a service provider record. 
+     * 
+     * If the record already exists (id value provided) then it is going to be updated,
+     * otherwise inserted into the database.
+     * 
+     * @param array $provider Contains the service provider data.
+     * @return int Returns the record id.
+     * @throws Exception When the record data validation fails.
+     */
+    public function add($provider) {
+        if (!$this->validate($provider)) {
+            throw new Exception('Provider data are not valid :' . print_r($provider, TRUE));
+        }
+        
+        if ($this->exists($provider) && !isset($provider['id'])) {
+            $provider['id'] = $this->find_record_id($provider);
+        }
+        
+        if (!isset($provider['id'])) {
+            $provider['id'] = $this->insert($provider);
+        } else {
+            $this->update($provider);
+        }
+        
+        return $provider['id'];
+    }
+    
+    /**
+     * Check whether a particular provider record already exists in the database.
+     *  
+     * @param array $provider Contains the provider data. The 'email' value is required 
+     * in order to check for a provider.
+     * @return bool Returns whether the provider record exists or not.
+     * @throws Exception When the 'email' value is not provided.
+     */
+    public function exists($provider) {
+        if (!isset($provider['email'])) {
+            throw new Exception('Provider email is not provided :' . print_r($provider, TRUE));
+        }
+        
+        // This method shouldn't depend on another method of this class.
+        $num_rows = $this->db
+                ->select('*')
+                ->from('ea_users')
+                ->join('ea_roles', 'ea_roles.id = ea_users.id_roles', 'inner')
+                ->where('ea_users.email', $provider['email'])
+                ->where('ea_roles.slug', DB_SLUG_PROVIDER)
+                ->get()->num_rows();
+        
+        return ($num_rows > 0) ? TRUE : FALSE;
+    }
+    
+    /**
+     * Insert a new provider record into the database.
+     *  
+     * @param array $provider Contains the provider data (must be already validated).
+     * @return int Returns the new record id.
+     * @throws Exception When the insert operation fails.
+     */
+    public function insert($provider) {
+        // Get provider's role id. 
+        $provider['id_roles'] = $this->get_providers_role_id();
+        
+        if (!$this->db->insert('ea_users', $provider)) {
+            throw new Exception('Could not insert provider into the database');
+        }
+        
+        return intval($this->db->insert_id());
+    }   
+    
+    /**
+     * Update an existing provider record in the database.
+     * 
+     * @param array $provider Contains the provider data.
+     * @return int Returns the record id.
+     * @throws Exception When the update operation fails.
+     */
+    public function update($provider) {
+        $this->db->where('id', $provider['id']);
+        
+        if (!$this->db->update('ea_users', $provider)) {
+            throw new Exception('Could not update provider record.');
+        }
+        
+        return intval($provider['id']);
+    }
+    
+    /**
+     * Find the database record id of a provider.
+     * 
+     * @param array $provider Contains the provider data. The 'email' value is required
+     * in order to find the record id.
+     * @return int Returns the record id.
+     * @throws Exception When the provider's email value is not provided.
+     */
+    public function find_record_id($provider) {
+        if (!isset($provider['email'])) {
+            throw new Exception('Provider email was not provided :' . print_r($provider, TRUE));
+        }
+        
+        // Get customer's role id
+        $result = $this->db
+                ->select('ea_users.id')
+                ->from('ea_users')
+                ->join('ea_roles', 'ea_roles.id = ea_users.id_roles', 'inner')
+                ->where('ea_users.email', $provider['email'])
+                ->where('ea_roles.slug', DB_SLUG_PROVIDER)
+                ->get();
+        
+        if ($result->num_rows() == 0) {
+            throw new Exception('Could not find provider record id.');
+        }
+        
+        return $result->row()->id;
+    }
+    
+    /**
+     * Validate provider data before the insert or  update operation is executed.
+     * 
+     * @param array $provider Contains the provider data.
+     * @return bool Returns the validation result.
+     */
+    public function validate($provider) {
+        $this->load->helper('data_validation');
+        
+        try {
+            // If a customer id is provided, check whether the record
+            // exist in the database.
+            if (isset($provider['id'])) {
+                $num_rows = $this->db->get_where('ea_users', 
+                        array('id' => $provider['id']))->num_rows();
+                if ($num_rows == 0) {
+                    throw new Exception('Provided record id does not exist in the database.');
+                }
+            }
+            // Validate required fields
+            if (!isset($provider['last_name'])
+                    || !isset($provider['email'])
+                    || !isset($provider['phone_number'])) { 
+                throw new Exception('Not all required fields are provided : ' . print_r($provider, TRUE));
+            }
+            
+            // Validate email address
+            if (!filter_var($provider['email'], FILTER_VALIDATE_EMAIL)) {
+                throw new Exception('Invalid email address provided : ' . $provider['email']);
+            }
+            
+            return TRUE;
+        } catch (Exception $exc) {
+            return FALSE;
+        }
+    }
+    
+    /**
+     * Delete an existing provider record from the database.
+     * 
+     * @param numeric $customer_id The record id to be deleted.
+     * @return bool Returns the delete operation result.
+     * @throws Exception When the provider id value is not numeric.
+     */
+    public function delete($provider_id) {
+        if (!is_numeric($provider_id)) {
+            throw new Exception('Invalid argument type $customer_id : ' . $provider_id);
+        }
+        
+        $num_rows = $this->db->get_where('ea_users', array('id' => $provider_id))->num_rows();
+        if ($num_rows == 0) {
+            return FALSE; // record does not exist
+        }
+        
+        return $this->db->delete('ea_users', array('id' => $provider_id));
+    }
+    
     /**
      * Get a specific row from the providers table.
      * 
diff --git a/src/application/models/secretaries_model.php b/src/application/models/secretaries_model.php
new file mode 100644
index 00000000..1fe27af0
--- /dev/null
+++ b/src/application/models/secretaries_model.php
@@ -0,0 +1,55 @@
+<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed.'); 
+
+class Admins_Model extends CI_Model {
+    /**
+     * Class Constructor
+     */
+    public function __construct() {
+        parent::__construct();
+    }
+    
+    public function add($secretary) {
+        
+    }
+    
+    public function exists($secretary) {
+        
+    }
+    
+    public function insert($secretary) {
+        
+    }   
+    
+    public function update($secretary) {
+        
+    }
+    
+    public function find_record_id($secretary) {
+        
+    }
+    
+    public function validate($secretary) {
+        
+    }
+    
+    public function delete($secretary) {
+        
+    }
+    
+    public function get_row($secretary_id) {
+        
+    }
+    
+    public function get_value($field_name, $secretary_id) {
+        
+    }
+    
+    public function get_batch($where_clause = '') {
+        
+    }
+    
+    
+}
+
+/* End of file secretaries_model.php */
+/* Location: ./application/models/secretaries_model.php */
\ No newline at end of file
diff --git a/src/application/views/backend/header.php b/src/application/views/backend/header.php
index 0e3e4b05..42324473 100644
--- a/src/application/views/backend/header.php
+++ b/src/application/views/backend/header.php
@@ -91,8 +91,8 @@
         
         <?php // PROVIDERS MENU ITEM 
               // ------------------------------------------------------ ?>
-        <a href="<?php echo $base_url; ?>backend/providers" class="menu-item">
-            Providers
+        <a href="<?php echo $base_url; ?>backend/users" class="menu-item">
+            Users
         </a>
         
         <?php // SETTINGS MENU ITEM 
diff --git a/src/application/views/backend/providers.php b/src/assets/js/backend_users.js
similarity index 83%
rename from src/application/views/backend/providers.php
rename to src/assets/js/backend_users.js
index b6eddc13..30893786 100644
--- a/src/application/views/backend/providers.php
+++ b/src/assets/js/backend_users.js
@@ -1,7 +1,6 @@
-<?php
-
-/*
- * To change this template, choose Tools | Templates
- * and open the template in the editor.
- */
-?>
+/* 
+ * To change this template, choose Tools | Templates
+ * and open the template in the editor.
+ */
+
+