HTTPS
The encrypted version of HTTP, the protocol your browser uses to talk to websites.
HTTPS wraps HTTP inside TLS, encrypting traffic so that observers on the path can't read or tamper with the content. The padlock in the address bar means HTTPS is in use; it does not mean the site itself is trustworthy.
HTTPS has become the de facto default; most browsers warn or block on plain HTTP. HTTPS is necessary but not sufficient for privacy — the destination site can still track you, and DNS queries can still leak metadata.