Transport Layer Security (TLS) is the protocol involved in getting the lock icon to appear in your browser next to the URL. Under the hood it uses a bunch of really cool numbers for encryption.…
From HOL Blocking to QUIC — how HTTP/1.1, HTTP/2, and HTTP/3 each made a different call on what to keep and what to let go, read through Path Dependency and the Innovator's Dilemma.