HTTP/2 is a significant overhaul to HTTP, the protocol for hypertext-based communication that handles the bulk of data transfer on the World Wide Web. This update has been a decade and half in the making, and soon servers and clients alike will all be able to use it.
What are the advantages of HTTP/2?
HTTP/2 makes significant improvements to the existing HTTP protocol, especially with page load times, such as:
Connections are now parallel and fully multiplexed, so multiple data assets can be transferred faster and more efficiently over the same TCP request.
The protocol is binary, so the commands in the form of 0s and 1s that are transferred over the wire are more efficient, unlike the human-readable commands used up to HTTP 1.1.
The new 'server push' concept allows the server to send resources in anticipation of the needs of the client, while still allowing the client to reject the pushed data.
Compressed HTTP headers that avoid the need to re-send headers.
How compatible is HTTP/2?
HTTP/2 strives to make HTTP better, but to get there, it has to work well with the existing infrastructure of the internet:
It supports all browsers, so if your site uses HTTP/2, there's no scenario where it prevents a visitor from accessing your site. Newer browsers that are compatible with HTTP/2 will work of course, but those aren't compatible will switch to HTTP 1.1 without so much as a hiccup. Of course, the new protocol doesn't affect how the site looks, just how well it performs or how quickly it loads.
It will directly work with your existing TLS certificate, and you don't need to tweak anything. However, do remember that only secured domains work with HTTP/2 right now, though this should change as more and more browsers add HTTP/2 cleartext support.
You can use HTTP/2 with major existing services like Cloudflare that support all the way up to even HTTP/3
Most hosting services enable HTTP/2 by default. The HTTP/2 web server from Verpex, for instance, works from the get go.
Testing
We can test that the enabled HTTP/2 on your website by using online tools such as KeyCDN's HTTP/2 Test (https://tools.keycdn.com/http2-test) and ensure that the protocol is indeed working for you.
