What are Private and Public keys?

Each Wallet has a Private Key and a Public Key. 

The Private Key is used to access your wallet and sign transactions in the blockchain, to send funds to other wallets. You must keep your private key offline and in a safe place, and never disclose it to anyone. 

The Public Key is an address used to receive funds. Anyone who has your public key is able to send ETH and Ethereum tokens to your wallet.

Similar to a mailbox, you have an address that can be used to send and receive emails (the public key), and a special key that unlocks the content of emails (the private key).