HTTP/2 is here! This new version of the Web’s most popular protocol is optimized for modern Web uses. Our networks are faster, our browsers are smarter, and our requirements are tougher than was the case when the previous version of HTTP was released. But it turns out that HTTP/2’s speed isn’t just a matter of switching out the old servers and switching in the new ones: The best practices that we developed for years, in order to make our Web sites fast and efficient, conflict in some ways with the ways in which HTTP/2 expects us to work. In this talk, Ilya Grigorik describes HTTP/2, and contrasts it with HTTP/1.x — less to understand the protocol itself, than to understand how it works.