HTTP/2
A binary, multiplexed version of HTTP that carries many concurrent requests over one TCP connection with header compression.
TechnicalQUIC
HTTP/3
The version of HTTP that runs over QUIC on UDP, removing transport-level head-of-line blocking and speeding up connection setup.
In full
QUIC combines transport and TLS handshakes, supports 0-RTT resumption, and keeps streams independent so a lost packet does not stall unrelated responses. The gains are largest on mobile and lossy networks, which is where Core Web Vitals are usually hardest to pass. It is typically enabled at the CDN with an `Alt-Svc` header advertising availability; origins can remain on HTTP/2.
Example
Enabling HTTP/3 at the edge reduces p75 mobile TTFB by roughly a fifth on a site with heavy traffic from congested networks.
Related terms
Time to First Byte
The interval between a navigation request starting and the first byte of the response arriving; a foundational input to LCP and a signal…
Content Delivery Network
A distributed network of edge servers that caches and serves content close to users, reducing latency and offloading the origin.
HTTPS
HTTP over TLS, encrypting traffic between browser and server; a lightweight Google ranking signal since 2014 and a baseline expectation…
Core Web Vitals
Google's set of three field-measured user experience metrics — LCP, INP and CLS — used as part of the page experience signals in ranking.