Asymmetric Key Cryptography (AKC)
This technique uses a pair of keys: a public and private key.
Messages are encrypted with a key (one in the two), and decrypted with the other key.
You only have one public key existing for its private key.
The public key is made available for anyone who requests it.
The private key must be kept secret by you only.
The RSA algorithm is the most well-known one.