HTTP/3 is the third major version of the Hypertext Transfer Protocol, built on QUIC rather than TCP. By eliminating TCP's head-of-line blocking and reducing connection setup time, HTTP/3 improves page load speed especially on unreliable or high-latency networks such as mobile connections. Faster connections reduce [Time to First Byte (TTFB)](/glossary/time-to-first-byte) and improve the overall user experience that feeds into [Core Web Vitals](/glossary/core-web-vitals). Most major CDNs and browsers support HTTP/3, and it is enabled automatically on many hosting platforms without any configuration changes needed.