Program, Account, Publickey and Keypair in Anchor

I'm beginner of solana programming using anchor. Now I have no clear understanding about these items.

 **Program, Account, PublicKey, Keypair**

Appreciate any help to understand what these are and relationship between each other.

All of these terms can be found in the terminology section of the Solana docs at https://docs.solana.com/terminology

• Program: The code that interprets instructions.
• Account: A record in the Solana ledger that either holds data or is an executable program.
• PublicKey: The public key of a keypair.
• Keypair: A public key and corresponding private key for accessing an account.