Public-key cryptography is a bit like having two special locks. One lock (the public key) is like a mailbox anyone can put things in. The other lock (the private key) is like the key to your house, which only you keep secret. With public-key cryptography, you can share the public key with anyone so they can send you encrypted messages (put things in your mailbox), but they'll need your private key (your house key) to decrypt those messages and actually read them.
