Note: This page is about the free Members plugin which is a User Roles and Capabilities editor. If you're looking for a plugin that will allow you more control over restricting your content and charge your member's for access, you should use MemberPress.
Members is a WordPress plugin that extends your control over your blog. It’s a user, role, and capability editor plugin that was created to make WordPress a more powerful CMS.
It puts you in control over permissions on your site by providing a user interface (UI) for WordPress’ powerful role and cap system, which is traditionally only available to developers who know how to code this by hand.
Role Editor: Allows you to edit, create, and delete roles as well as capabilities for these roles.
Multiple User Roles: Give one, two, or even more roles to any user.
Explicitly Deny Capabilities: Deny specific caps to specific user roles.
Clone Roles: Build a new role by cloning an existing role.
Content Permissions: Gives you control over which users (by role) have access to post content.
Shortcodes: Shortcodes to control who has access to content.
Widgets: A login form widget and users widget to show in your theme’s sidebars.
Private Site: You can make your site and its feed completely private if you want.
Plugin Integration: Members is highly recommended by other WordPress developers. Many existing plugins integrate their custom roles and caps directly into it.