A private key is a long sequence of numbers and/or characters that allows the holder of that key to access their wallet and send transactions on the blockchain. Every blockchain address has an associated private key.
Think of it as a kind of password to access your crypto coins.
See below for a sample of a Bitcoin private key:
Because anyone with the private key can access the wallet’s coins, it is very important to keep it secure.
When referring to hardware or paper wallets, this is a popular way of securely storing the private key.
It is important to note that while the private key should always be kept secure, your wallet address is public. Anyone can view the wallet’s balance and its transactions on a the blockchain. But they cannot access the wallet without the private key.
See below for a sample of a Bitcoin wallet address: