HTTP/2
Definition
A major upgrade to how browsers and servers communicate. Allows multiple files to download simultaneously, making websites significantly faster.
What is HTTP/2?
HTTP/2 is the second major version of the HTTP protocol – the rules for how browsers request files from servers. Released in 2015, it brought significant performance improvements over the original HTTP/1.1.
Over 95% of browsers support HTTP/2, and most websites now use it.
Why HTTP/2 Matters
HTTP/1.1 had a fundamental limitation: browsers could only request files one at a time per connection. To download a page with 50 files, the browser had to wait for each one sequentially.
HTTP/2 allows multiple files to download simultaneously over a single connection – called multiplexing.
Key Improvements
Multiplexing
Multiple requests and responses happen simultaneously. No more waiting in line.
Header Compression
HTTP headers are compressed, reducing redundant data on every request.
Server Push
Servers can proactively send files they know the browser will need – like CSS files – before being asked.
Binary Protocol
Data is sent in binary format, more efficient for computers to process than text.
HTTP/1.1 vs HTTP/2
| Factor | HTTP/1.1 | HTTP/2 |
|---|---|---|
| Connections | Multiple, one file each | Single, many files |
| Header overhead | High redundancy | Compressed |
| Priority | None | Files can be prioritised |
| SSL required | No | Effectively yes |
Real-World Impact
Sites switching from HTTP/1.1 to HTTP/2 typically see:
- 20-50% improvement in load time
- Better performance on mobile
- Improved Core Web Vitals scores
How to Enable HTTP/2
Requirements
- HTTPS (SSL certificate) – HTTP/2 practically requires it
- Server support – Apache 2.4.17+, Nginx 1.9.5+, or modern CDN
Most Sites Already Have It
If your site uses HTTPS and decent hosting, you likely already have HTTP/2. Check in Chrome DevTools: Network tab > right-click columns > enable Protocol. You'll see "h2" for HTTP/2.