“Not your keys, not your coins” is a powerful Bitcoin mantra, meaning if your wallet doesn’t give you exclusive access to your private keys, you don’t actually own bitcoin. Instead, a third party — like an exchange — will hold it for you just like a bank keeps custody of your money.”

https://bitcoinmagazine.com/guides/what-is-a-wallet?utm_source=carrot&utm_medium=partner&utm_campaign=carrot_share