TLS

TLS is the padlock. It encrypts the connection and proves the server is genuinely the one whose name is in the address bar.

Both halves matter and people usually only think about the first. Encryption without the identity check would give you a private conversation with whoever intercepted it. Correctly configured, it stops eavesdropping and impersonation on the wire. What it cannot do is say anything about whether the site at the far end is honest, which is a different question entirely.