Comparison of HTTP Versions

The Hypertext Transfer Protocol (HTTP) has evolved through various versions, each bringing improvements in performance, security, and usability. Below is a comparison of the major HTTP versions: HTTP/0.9, HTTP/1.0, HTTP/1.1, HTTP/2, HTTP/3, and HTTP with QUIC.

Feature	HTTP/0.9	HTTP/1.0	HTTP/1.1	HTTP/2	HTTP/3	HTTP with QUIC
Protocol Type	Text-based	Text-based	Text-based	Binary	Binary	Binary
Connection Type	Non-persistent	Non-persistent	Persistent	Persistent	Persistent	Persistent
Request Types	GET only	GET, HEAD	GET, POST, HEAD, OPTIONS	Multiplexed streams	Multiplexed streams	Multiplexed streams
Response Formats	HTML only	HTML, Status Codes	HTML, Status Codes	Binary, HTTP/2 framing	Binary, HTTP/3 framing	Binary, HTTP/3 framing
Compression	None	None	gzip	HPACK	QPACK	QPACK
Security	None	Optional (HTTPS)	Optional (HTTPS)	Mandatory (TLS)	Mandatory (TLS)	Built-in encryption
Latency	High	Moderate	Moderate	Low	Very low	Very low
Head-of-Line Blocking	Yes	Yes	Yes	No	No
Connection Migration	No	No	No	No	Yes	Yes

Key Differences

• Performance: HTTP/2 and HTTP/3 significantly reduce latency through multiplexing, which allows multiple streams of data to be sent simultaneously without blocking.

• Security: While HTTPS is optional in earlier versions, it is mandatory for HTTP/2 and HTTP/3, enhancing security across all communications.

• Compression: HTTP/1.1 introduced gzip compression, while HTTP/2 and HTTP/3 use more efficient binary encoding methods (HPACK and QPACK).

• Connection Management: HTTP/1.1 introduced persistent connections, but HTTP/2 and HTTP/3 take it further with enhanced multiplexing capabilities, reducing the overhead of establishing new connections.

Understanding the differences between HTTP versions is crucial for web developers and system architects when optimizing web applications and ensuring compatibility.