Explain HTTP/2 vs HTTP/3.

HTTP/2 vs HTTP/3 compares two web protocols, where HTTP/3 (built on QUIC over UDP) delivers faster, more reliable connections than HTTP/2 (built on TCP).

When to Use

HTTP/3 is best for low-latency use cases like video streaming, gaming, and mobile browsing where network conditions are less stable. HTTP/2 remains reliable for environments where QUIC isn’t supported yet.

Example

Think of loading a social media feed: with HTTP/2, a single lost packet can stall all images (head-of-line blocking). With HTTP/3, only the missing piece is retried while others load smoothly.

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Why Is It Important

Understanding HTTP/2 vs HTTP/3 is key to optimizing web performance. It impacts user experience, SEO (through faster load times), and interview discussions on system design.

Interview Tips

In interviews, explain that HTTP/3 solves TCP’s limitations by using QUIC to avoid head-of-line blocking and reduce handshake latency. Emphasize real-world benefits like faster streaming and mobile browsing.

Trade-offs

HTTP/3 uses more CPU due to encryption overhead and requires modern browser/server support. HTTP/2 is simpler to deploy but slower under poor networks.