---
title: "HTTP/2"
description: "HTTP/2 speeds up page loads with multiplexing, header compression and prioritization. Learn how it differs from HTTP/1.1 and why it needs HTTPS."
url: "https://nodea.io/en/glossary/http-2"
lang: "en"
updated: "2026-07-13"
---

# HTTP/2

> HTTP/2 is the second major version of the HTTP protocol, significantly speeding up page loads by multiplexing many requests over a single connection and compressing headers. It keeps full semantic compatibility with HTTP/1.1.

**HTTP/2** is the second major version of the [HTTP](https://nodea.io/en/glossary/http) protocol, published in 2015 (RFC 7540) and based on Google's earlier SPDY protocol. It preserves the same semantics as HTTP/1.1 — the same methods, status codes and headers — but completely changes how data is transmitted in order to speed up modern, complex web pages.

## How HTTP/2 works

The key innovation is **multiplexing** — many requests and responses can travel in parallel over a single TCP connection. In HTTP/1.1 the browser had to open several separate connections and suffered from head-of-line blocking, where one slow resource held up the others. HTTP/2 solves this at the application level. Its other improvements include:

- **Header compression** (HPACK) — cuts the repetitive metadata overhead in every request.
- **Stream prioritization** — the browser signals which resources matter most.
- **Binary framing** — data is split into frames, which is more efficient and less error-prone than the text-based HTTP/1.1.

The result is faster page rendering and a lower [TTFB](https://nodea.io/en/glossary/ttfb), which translates directly into better [Core Web Vitals](https://nodea.io/en/glossary/core-web-vitals) scores.

## Practical application

HTTP/2 is now widely supported by Apache, Nginx and LiteSpeed servers and by CDNs, and enabling it usually comes down to server configuration and having an [HTTPS](https://nodea.io/en/glossary/https) certificate. Because multiplexing removes the cost of many connections, old HTTP/1.1-era optimization techniques — concatenating CSS/JS files or sharding resources across multiple domains — lose their point or become counterproductive. The next step in the protocol's evolution is [HTTP/3](https://nodea.io/en/glossary/http-3), which moves transport from TCP to the QUIC protocol.

It's worth noting one limitation: HTTP/2 multiplexing works at the application level but still runs over a single TCP connection. Losing one packet then stalls data delivery across all streams — the so-called transport-level head-of-line blocking. In networks with high packet loss this issue is only resolved by HTTP/3, which makes the two versions complementary steps on the road to a faster web.

### Does HTTP/2 require an SSL certificate?

Formally the specification allows HTTP/2 without encryption, but in practice all browsers support it only over HTTPS. As a result, a site needs a valid TLS certificate to use HTTP/2 — which is the standard today anyway.

### Do I need to change my site's code to enable HTTP/2?

No. HTTP/2 operates at the transport level and is transparent to the application — the web server just needs to support it. It is worth revisiting old HTTP/1.1-era optimizations, however, such as file concatenation or domain sharding, since multiplexing can make them unnecessary or even counterproductive.

## Related

- [HTTP](https://nodea.io/en/glossary/http)
- [HTTP/3](https://nodea.io/en/glossary/http-3)
- [HTTPS](https://nodea.io/en/glossary/https)
- [TTFB](https://nodea.io/en/glossary/ttfb)
- [Core Web Vitals](https://nodea.io/en/glossary/core-web-vitals)

---

Languages: [pl](https://nodea.pl/pl/slownik-pojec/http-2.md)  
Site index: [llms.txt](https://nodea.io/en/llms.txt)