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HTTP/3: Everything you need to know About Next-Generation Web Protocol

HTTP/3, the next generation of web protocol, is more secure, has ultra-high performance, encrypts by default, reduces latency, and has many more features. 

The experimental protocol HTTP-over-QUIC is set to be renamed as HTTP/3, according to officials at the Internet Engineering Task Force (IETF). 

This move marks a significant development in the evolution of the HTTP protocol, bridging the gap from HTTP/1.1 (released in 1999) to HTTP/2 (released in 2015)


The HTTP/3, introduced in June 2022, is built on the foundation of the QUIC protocol originally developed by Google. The decision to rename aligns with the ongoing efforts to advance and standardize internet protocols.

What is HTTP/3?

HTTP/3 is a significant update to the way information is transferred on the internet. It builds upon the Hypertext Transfer Protocol (HTTP), which is a fundamental technology for loading websites. Unlike its predecessors, HTTP/3 uses a protocol called QUIC, which was developed by Jim Roskind at Google. QUIC encrypts data and allows multiple streams of information to be sent over a single connection, making the transfer more efficient.

This update is designed to enhance the user experience by improving performance, reliability, and security. It represents a notable advancement in how web browsers and servers communicate, offering more than just incremental speed improvements seen in previous versions of HTTP.

Previous versions of HTTP

Previous versions of HTTP, like HTTP/1.1, use whitespace-delimited text fields for conveying messages. Although these messages are readable by humans, this approach introduces complexity in parsing and allows for varying behavior.

HTTP Semantics

In HTTP/1.1, there is no built-in multiplexing layer, leading to the use of multiple TCP connections to handle requests simultaneously. However, this approach negatively affects congestion control and network efficiency because TCP’s congestion control is not shared across these connections.

HTTP/2 addressed some of these issues by introducing a binary framing and multiplexing layer to improve latency without modifying the transport layer. However, the parallel nature of HTTP/2’s multiplexing is not transparent to TCP’s loss recovery mechanisms, causing a lost or reordered packet to stall all active transactions, regardless of their direct impact on the lost packet.

What is QUIC?

QUIC (Quick UDP Internet Connections) is a modern transport protocol designed to reduce latency compared to traditional TCP. At a high level, QUIC resembles the combination of TCP, TLS, and HTTP/2, but it operates on top of UDP. 

Unlike TCP, which is deeply embedded in operating system kernels and middlebox firmware, making substantial changes to it is challenging. However, QUIC, being built on UDP, can overcome these limitations.


Source: Auvik

Key features of QUIC that set it apart from the combination of TCP, TLS, and HTTP/2 include:

  • Dramatically reduced connection establishment time: QUIC significantly speeds up the process of establishing connections compared to traditional methods.
  • Improved congestion control: QUIC incorporates better mechanisms for managing network congestion, enhancing overall performance.
  • Multiplexing without head-of-line blocking: QUIC allows for more efficient multiplexing of data streams without the issues of head-of-line blocking seen in traditional protocols.
  • Forward error correction: QUIC includes features for correcting errors that may occur during data transmission, contributing to more reliable communication.
  • Connection migration: QUIC supports the seamless migration of connections between network interfaces or addresses, providing enhanced flexibility in maintaining connections.

QUIC and HTTP/3 Encrypted by Default

HTTP/3’s default encryption automatically protects communication between clients and servers, unlike traditional setups. This offers significant advantages:

  • Enhanced Security: QUIC encrypts the entire connection at the transport layer, eliminating vulnerabilities.
  • Reduced Latency: By combining handshakes, QUIC establishes connections faster than HTTP/2.
  • Improved Privacy: QUIC encrypts both data and connection metadata, preventing information leaks.
  • Simplified Deployment: Default encryption removes the need for manual configuration.
  • Universal Security: Guaranteed encryption prevents accidental exposure of sensitive data.

Overall, QUIC and HTTP/3’s default encryption provide a significant boost to web security and privacy, paving the way for a safer internet.

How much of HTTP/3 has actually been Used?

The latest version of the HTTP protocol, HTTP/3, has been officially standardized by the Internet Engineering Task Force (IETF), the organization responsible for defining Internet technologies. 

Since its standardization, both HTTP/3 and the associated QUIC protocol have gained widespread adoption on the public web. 

HTTP/3 growth

The extent of this adoption varies based on sources and measurement methods, with reported HTTP/3 support ranging from 19% to over 50% of web servers and networks globally.

Major companies such as Google and Meta heavily use these new protocols, contributing to a significant portion of current Internet traffic already relying on HTTP/3. 

It’s worth noting that the blog post you are currently reading was likely loaded over HTTP/3, showcasing the prevalence of this protocol in modern web communications.

Final Words

HTTP/3 represents a significant leap forward in the evolution of web protocols, promising improved performance, enhanced security, and better user experiences. With its foundation in the QUIC transport protocol, HTTP/3 optimizes data transfer over the internet, reducing latency and addressing the shortcomings of previous versions. 

The widespread adoption by major tech players and increasing support from web servers globally underscore its importance in shaping the future of web communications. As HTTP/3 continues to gain traction, users can anticipate a more efficient and secure browsing experience.

FAQs on HTTP/3

1. How does HTTP/3 differ from HTTP/2 and HTTP/1.1?

HTTP/3 introduces significant improvements over HTTP/2 and HTTP/1.1. It utilizes the QUIC transport protocol, reducing connection establishment times, enhancing congestion control, and providing forward error correction. These optimizations result in a faster, more reliable, and secure web browsing experience.

2. What is QUIC, and how does it relate to HTTP/3?

QUIC, or Quick UDP Internet Connections, is a transport protocol developed by Google. HTTP3 operates over QUIC, benefiting from its reduced latency, improved congestion control, multiplexing capabilities, and support for connection migration.

3. Why is encryption significant in HTTP/3?

HTTP/3 encrypts connections by default at the transport layer, offering improved security. This differs from previous versions, where encryption occurred separately at the application layer. Encrypting by default helps protect user data, reduces latency, and ensures a safer browsing experience.

4. How widely is HTTP/3 adopted?

HTTP/3 has gained substantial adoption, with varying reports indicating support from 19% to over 50% of web servers and networks globally. Major companies like Google and Meta heavily use HTTP/3, contributing to its prevalence in current Internet traffic.

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