Public Key
In plain terms
The shareable half of an asymmetric key pair.
Going deeper
A public key can be freely distributed to encrypt messages to its owner or verify their signatures, while the matching private key stays secret. It enables secure communication without sharing secrets.
Under the hood
Pairs with a private key; encrypting with the public key means only the private key decrypts.
Examples
TLS certificates, SSH keys, PGP, encrypting to a recipient, signature verification.
Think of it like...
Like an open mailbox slot anyone can drop letters into, but only the owner has the key to retrieve them.