Web site addresses all begin with http or https. This indicates that they use the Hypertext Transport Protocol, which is the way that web browsers communicate with web servers. Not to be confused with HTML, which is the language used to create web pages themselves.
The HTTP specification has been stuck at version 1.1 for the past 15 years or so, but the new version 2 is now rapidly becoming popular. As well as the additional features that it offers for developers, it also includes some significant speed improvements. So if you're viewing a web site that supports version 2, from a browser that also supports it, you'll see those speed increases.
But how to find out whether your web browser supports HTTP/2? Thankfully there's an easy way. Just go the link below to find out. Not only will the page automatically check whether your browser supports HTTP/2, it'll also demonstrate the speed increase. It does this by downloading a set of images, using both version 1 and 2, and shows you the time that each version took to download.
Link to Test If Your Browser Supports HTTP/2