HTTP explained in comic form
Web developer Mariko Kosaka put together a delightful set of drawings explaining what HTTP actually is, and the differences between HTTP1.x and HTTP2.
The tl;dr: HTTP is the protocol servers and browsers use to talk to each other, and HTTP2 is a more efficient way of doing so that corrects some of the mistakes we made with HTTP1.x.
Go check out the drawings, though. They’re fantastic!