WordPress Multisite is the Wizard of Oz of WordPress. It is all-powerful and feared by many. If you are an ordinary WordPress developer, pay no attention to the code behind the curtain!
Meanwhile, in a recent WordPress.tv video, Jeremy Felt pulls back the curtain during the WordCamp Vancouver 2015 to give us a “straight no chaser” tour of WordPress Multisite. In his presentation titled Behind The Curtain Of WordPress Multisite, Felt provides an excellent primer for those unfamiliar with what code is under the hood of WordPress Multisite that makes it function as a single codebase.
Felt has an incredible level of knowledge of the parts of the WordPress core code that make WordPress Multisite work, and why some of the decisions in developing WordPress Multisite where made. Many of the insights that Felt makes still impact WordPress Multisite to this day.