Evolution and versions of the HTTP protocol: a complete guide.

The Hypertext Transfer Protocol (HTTP) is the foundation of web communication. Over more than three decades, this protocol has evolved to offer faster, more secure, and more efficient websites. Each version has introduced improvements in performance, security, compression, parallelization, and connection handling, enabling the development of modern web applications, online stores, and dynamic platforms.

In this guide, you will find a clear and updated explanation of all HTTP versions, from its beginnings to the most modern standard used by current browsers.

HTTP/0.9 (1991) – The first version of the protocol.

The first version of the protocol, known as Simple HTTP, was created to serve static documents.

Key features:

• It only allowed the GET method.
• It did not include headers or status codes.
• It could only deliver HTML documents.
• It worked with extremely basic connections.

It was a sufficient solution for the early days of the web, although very limited for any current application.

HTTP/1.0 (1996) – The beginning of the modern web.

With HTTP/1.0 came the true structure of the protocol as we know it.

Important improvements:

• Headers were added to requests and responses.
• Introduction of status codes (200, 404, 500...).
• Support for different content types via `Content-Type`.
• Connections were non-persistent: one connection for each requested resource.

This last point led to slow loading times, especially on pages with multiple images or scripts.

HTTP/1.1 (1997) – The most used version for years.

HTTP/1.1 became the dominant standard for decades and is still very present today.

Main improvements:

• Persistent (keep-alive) connections.
  
• Better cache management with `ETag` and `Cache-Control`.
  
• Support for pipelining (though rarely adopted due to its problems).
  
• Improved error and redirection handling.
  
• More efficient compression using `gzip`.

Its stability and universal compatibility keep it active on millions of servers.

HTTP/2 (2015) – A big leap in speed and performance.

HTTP/2 was designed to resolve the limitations of HTTP/1.1 and accelerate the web.

Highlighted features:

• Multiplexing: multiple requests over a single connection.
  
• Header compression using HPACK.
  
• Resource prioritization system.
  
• Better distribution of static content.
  
• Popularization of server push, though currently deprecated.

It represented a significant improvement in loading times, especially on sites with many resources.

HTTP/3 (2019–current) – The most modern version of the protocol

HTTP/3 introduces one of the biggest transformations by building on QUIC, a new protocol that runs over UDP instead of TCP.

Key advantages:

• Faster connections thanks to a reduced handshake.
• Better performance in: mobile networks, environments with packet loss, and unstable connections.
• Each stream is independent, avoiding typical TCP blocking.
• Designed for a modern and global web.

Today it is supported by browsers like Chrome, Edge, and Firefox, and used by platforms like Google and Cloudflare.

Which HTTP version is used today?

Currently:

• HTTP/2 dominates global traffic due to its high performance.
• HTTP/3 is growing rapidly thanks to its excellent latency and mobile behavior.
• HTTP/1.1 remains present as a compatibility standard.

For any modern project —including corporate websites, landing pages, or online stores— it is advisable to enable HTTP/2 and HTTP/3 on the server or CDN to optimize loading speed, improve Core Web Vitals, and offer a better user experience.

Conclusions

HTTP has constantly evolved to adapt to the needs of an increasingly complex web. From the simple HTTP/0.9 to the modern HTTP/3, each version has brought improvements in speed, security, and efficiency.

Frequently Asked Questions

What is the main difference between HTTP/2 and HTTP/3?

HTTP/2 uses TCP, while HTTP/3 uses QUIC, based on UDP. This allows HTTP/3 to avoid Head-of-Line (HOL) blocking and offer much faster and more stable connections, especially on mobile networks or with packet loss.

Is it necessary to update my site to HTTP/3?

It is not mandatory, but it is recommended. HTTP/3 improves speed and stability, which benefits metrics like LCP, FID, and TTFB. Furthermore, its adoption is rapidly growing in modern browsers and CDNs.

What HTTP version do most websites use today?

Currently, HTTP/2 dominates global traffic, as it is compatible with all modern browsers and offers significant improvements without requiring infrastructure changes. HTTP/3 is increasing its adoption, while HTTP/1.1 remains an option for compatibility.