First, HTTP/1.1. It’s outdated, and everyone knows it. Google came up with the SPDY protocol which some webservers added support for and some sites used, but it didn’t catch on. Over time, it morphed into today’s specification for HTTP/2, a much needed iteration of the HTTP protocol every website uses today to serve you its content. It is much faster, for a variety of reasons. See Mark McDonnell’s excellent write-up of all the benfits of HTTP/2 for a holistic look at the best parts of HTTP/2.
Run a website? Support HTTP/2 today! Most web browsers now support it out of the box, so do yourself and your visitors on slow connections a favour and upgrade!
If all you care about are folks in rich areas in first-world countries, then don’t do anything. You’re all set!
If you care about folks on slow connections, support HTTP/2 and reduce the resources which your pages load. Most of Asia, Africa, and South America, and many in Europe and North America, too, will thank you.