What is WP Multisite?
A WP multisite network allows to run and manage multiple WP sites from a single installation. You can create new websites instantly and manage them using the same username and password. You can even allow other users to signup and create their own blogs on your domain.
To enable Multisite, you need to access your website using an FTP client or cPanel file manager and open wp-config.php file.
You need to add this line to your wp-config.php file just before the /* That’s all, stop editing! Happy blogging. */ line.
/* Multisite */
define( 'WP_ALLOW_MULTISITE', true );
Setting up The Network
Now that you have successfully enabled the Multisite Network feature, it is time to set up your network. Before you do that, first thing you need to do is deactivate all plugins on your site. After that, you need to go to Tools » Network Setup to configure your multisite network.
Please follow the instruction there and edit wp-config.php and .htaccess files. Log in again and it top left corner you will have Network Admin menu. Now you are ready to create and enjoy managing WP sites from a single installation.