From HTTP/2 in Action by Barry Pollard.
The Hypertext Transfer Protocol, or HTTP, defines how data travels on the web, including the billions of web page requests happening each day. HTTP/2 is the most significant upgrade to the protocol in 20 years. The new standard is more efficient, which means faster, safer web traffic. HTTP/2 in Action introduces HTTP/2 and teaches you everything you need to use it effectively! This diagram compares the function HTTP/1.1 and HTTP/2.