What is WIF (wallet import format)?
The text format a single private key takes when you export or import it — a string starting with 5, K or L.
A raw private keyPrivate keyThe secret number that lets you spend your bitcoin. Whoever knows it controls the coins, so it must never be shared. is just a number. WIF wraps it with a checksum and network marker so wallets can move it between apps without typos going unnoticed. Imported WIF keys sit outside a wallet's recovery wordsRecovery words (seed phrase)A list of 12, 15, 18, 21 or 24 words that can restore wallet keys. Anyone who has them can take your bitcoin. — back them up separately.
Treat a WIF string like the key it is: anyone who reads it can spend the coins. Most people never need one; it comes up when sweeping a paper walletPaper walletA key printed or written on paper rather than kept on a device. Once common, it's now mostly outdated and risky to make safely. or moving an old key.