# Private Key 1. A private key in cryptography is the secret that is used prevent unauthorized access to certain data or systems. In blockchain systems, the private key is usually used to control access to cryptocurrency tokens such as bitcoin or factoids. Protecting your private keys is critical, as failing to do so will leave your systems, data, or wallets exposed. 3. A private key is a string of data that allows you to access the tokens in a specific wallet. They act as passwords that are kept hidden from anyone but the owner of the address. Private keys must never be revealed to anyone but you, as they allow you to spend the coins from your coin wallet through a cryptographic signature. There are different types of wallets such as online wallets, mobile wallets, desktop wallet, hardware wallets or paper wallets. The category of each wallet is determined by where private keys are stored. Online wallets are mostly provided by exchanges and keep user’s private keys on their servers. If the service provider goes offline users would lose access to their funds. Hardware wallets for example store user’s private keys in a secure device which looks like a USB flash drive. 4. A string of letters and numbers that are used for sending cryptocurrency. The private key should be kept secret because it enables spending with the cryptocurrency wallet. 5. A private key is a string of data that shows you have access to bitcoins in a specific wallet. Private keys can be thought of as a password; private keys must never be revealed to anyone but you, as they allow you to spend the bitcoins from your bitcoin wallet through a cryptographic signature. 7. Each time a user runs a cryptocurrency wallet for the first time a public-private key pair gets generated. The private key is a randomly generated number which allows users to transact over the blockchain. It is locally stored and kept secret. Each time a Bitcoin gets sent a private key has to sign the transaction. This action is automatically executed by the wallet software. When a wallet asks users to do a backup what this means is that the users must secure their private key. There are different types of wallets such as online wallets, mobile wallets, desktop wallet, hardware wallets or paper wallets. The category of each wallet is determined by where private keys are stored. Online wallets are mostly provided by exchanges and keep user’s private keys on their servers. If the service provider goes offline users would lose access to their funds. Hardware wallets for example store user’s private keys in a secure device which looks like a USB flash drive. 7. A unique string of data that represents proof of identification within the blockchain, including the right to access and own that participant’s wallet within a cryptocurrency. It must be kept secret: it is effectively a personal password. 8. The private portion of a keypair which can create signatures that other people can verify using the public key. 9. A private key is a secret piece of data that proves your right to spend bitcoins from a specific wallet through a cryptographic signature. Your private key(s) are stored in your computer if you use a software wallet; they are stored on some remote servers if you use a web wallet. Private keys must never be revealed as they allow you to spend bitcoins for their respective Bitcoin wallet.