# 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.

<table><thead><tr><th width="162">Feature</th><th width="106">HTTP/0.9</th><th width="111">HTTP/1.0</th><th width="112">HTTP/1.1</th><th width="118">HTTP/2</th><th width="118">HTTP/3</th><th>HTTP with QUIC</th></tr></thead><tbody><tr><td><strong>Protocol Type</strong></td><td>Text-based</td><td>Text-based</td><td>Text-based</td><td>Binary</td><td>Binary</td><td>Binary</td></tr><tr><td><strong>Connection Type</strong></td><td>Non-persistent</td><td>Non-persistent</td><td>Persistent</td><td>Persistent</td><td>Persistent</td><td>Persistent</td></tr><tr><td><strong>Request Types</strong></td><td>GET only</td><td>GET, HEAD</td><td>GET, POST, HEAD, OPTIONS</td><td>Multiplexed streams</td><td>Multiplexed streams</td><td>Multiplexed streams</td></tr><tr><td><strong>Response Formats</strong></td><td>HTML only</td><td>HTML, Status Codes</td><td>HTML, Status Codes</td><td>Binary, HTTP/2 framing</td><td>Binary, HTTP/3 framing</td><td>Binary, HTTP/3 framing</td></tr><tr><td><strong>Compression</strong></td><td>None</td><td>None</td><td>gzip</td><td>HPACK</td><td>QPACK</td><td>QPACK</td></tr><tr><td><strong>Security</strong></td><td>None</td><td>Optional (HTTPS)</td><td>Optional (HTTPS)</td><td>Mandatory (TLS)</td><td>Mandatory (TLS)</td><td>Built-in encryption</td></tr><tr><td><strong>Latency</strong></td><td>High</td><td>Moderate</td><td>Moderate</td><td>Low</td><td>Very low</td><td>Very low</td></tr><tr><td><strong>Head-of-Line Blocking</strong></td><td>Yes</td><td>Yes</td><td>Yes</td><td>No</td><td>No</td><td></td></tr><tr><td><strong>Connection Migration</strong></td><td>No</td><td>No</td><td>No</td><td>No</td><td>Yes</td><td>Yes</td></tr></tbody></table>

### 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.

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