drupal/core/modules/basic_auth/basic_auth.module

<?php

/**
 * @file
 * Provides an HTTP Basic authentication provider.
 */

use Symfony\Component\HttpFoundation\Request;

/**
 * Implements hook_help().
 */
function basic_auth_help($route_name, Request $request) {
  switch ($route_name) {
    case 'help.page.basic_auth':
      $output = '';
      $output .= '<h3>' . t('About') . '</h3>';
      $output .= '<p>' . t('The HTTP Basic Authentication module supplies an <a href="http://en.wikipedia.org/wiki/Basic_access_authentication">HTTP Basic authentication</a> provider for web service requests. This authentication provider authenticates requests using the HTTP Basic Authentication user name and password, as an alternative to using Drupal\'s standard cookie-based authentication system. It is only useful if your site provides web services configured to use this type of authentication (for instance, the <a href="!rest_help">RESTful Web Services module</a>). For more information, see <a href="!hba_do">the online documentation for the HTTP Basic Authentication module</a>.', array('!hba_do' => 'https://drupal.org/documentation/modules/basic_auth', '!rest_help' => \Drupal::url('help.page', array('name' => 'rest')))) . '</p>';
      return $output;
  }
}