Backend Users module 

Backend Users submodule 

Will be shown by default unless you have chosen a different submodule from the dropdown in the module header. You can Create new backend users or Administrators here, enable and disable access for your users, reset password of non-admins, etc.

1. Edit user settings.
2. Disable or enable user.
3. Delete user.
4. Reset password - only available if the user has an email address in their settings. Will send an email to the user asking them to enter a new password.
5. View user details, including a combined view of their permissions incorporating all their groups and settings in the user record. Overview of User TSconfig reference that apply to this user.
6. The general info module for the record of the backend user including references from other database records.
7. Compare the permissions of two or more backend users by adding them to the compare list. You can then click the "Compare selected backend users" button.
8. Simulate the backend user to try out the permissions.

Backend user groups submodule 

Gives you an overview of all backend user groups and allows you to edit, disable, delete and compare permissions of groups.

Online users submodule 

Shows you a list of all currently online users, including those who logged in during the last two hours but never logged out.

File mounts submodule 

Allows you to view, edit, disable or delete file mounts.

Static user TSconfig from an extension 

A backend user and a backend user group each have a field Include static TSconfig in their Options tab. It lists the user TSconfig files that the installed extensions offer, and the user or the group reads the files you select.

Prefer such a file over the TSconfig field above it. That field keeps its content in the database, where an upgrade cannot see it. A file lives in the extension or the site package, next to the rest of the configuration.

An extension offers a file for backend users in Configuration/TCA/Overrides/be_users.php:

<?php

declare(strict_types=1);

use TYPO3\CMS\Core\Utility\ExtensionManagementUtility;

defined('TYPO3') or die();

ExtensionManagementUtility::registerUserTSConfigFile(
  'my_extension',
  'Configuration/TsConfig/User/Editor.tsconfig',
  'Editor',
);

For a group, call ExtensionManagementUtility::registerUserGroupTSConfigFile() in Configuration/TCA/Overrides/be_groups.php instead:

<?php

declare(strict_types=1);

use TYPO3\CMS\Core\Utility\ExtensionManagementUtility;

defined('TYPO3') or die();

ExtensionManagementUtility::registerUserGroupTSConfigFile(
  'my_extension',
  'Configuration/TsConfig/User/NewsEditors.tsconfig',
  'News editors',
);

Both calls take the extension key, the path of the file inside that extension, and the title of the entry. TYPO3 appends the extension key in brackets to the title, so the entry above reads Editor (my_extension). The title is therefore a plain string: a LLL: reference does not get translated here. TYPO3 also drops every comma from the path, because a comma separates the selected entries in the field.