WP Multisite enables multiple websites to be powered off a single install. This opens plenty of new possibilities for developers and companies to create larger websites, enterprise level solutions, or just for logically organizing a website’s content and dividing tasks.
“A feature of WP 3.0 and later versions that allows multiple virtual sites to share a single installation.”
Using a Multi Site installation will add the ability of running multiple sites with a single install of WP. This set-up is great for creating a network of sites with easy administration of each individual website. All sites can share the same plugins and theme, making the update process easy and flawless. This workflow works great for large organizations running multiple sites under the same brand. The Multi site setup is almost exactly the same as updating any site. All of your network’s themes and plugins are stored just once, no matter how many sites you use them on, meaning you’ll be using significantly less server space than if you used a separate installation for each site.