WordPress does not come with the ability for Single Sign On (SSO). SSO can be added easily by implementing OAuth2 using our WordPress plugin.
Why would a WordPress website need a Single Sign-On client?
In many cases, a larger company wants to launch small quick sites outside of their main site. This is common for Microsoft and other companies of their size. They tend to call these sites popups or satellite sites. Often times satellite sites need to use some user data from the main site. OAuth 2.0 is by far the easiest and best way to accomplish this.
We have developed a Single Sign-On client plugin that makes it easy to link one WordPress site to another. The Plugin can be found at https://wordpress.org/plugins/single-sign-on-client/ and if completely free. Simply set up WP OAuth Server on your main site. Then install the Client plugin on any other WordPress site. The SSO plugin adds a plugin to the login page of WordPress that allows SSO from the main site.
Download the SSO plugin: https://wordpress.org/plugins/single-sign-on-client/