Tokenization
Replacing sensitive card data with a non-sensitive token that can be stored and reused safely.
Tokenization replaces a card number with a substitute value, a token, that is useless if stolen. Your systems store and reuse the token while the real card number stays inside the provider's secure vault.
The immediate benefit is PCI scope. If card numbers never reach your servers, most of the storage and encryption requirements simply do not apply to you, which is the single largest reduction in compliance burden available to a merchant.
The operational benefit matters just as much for recurring businesses. Tokens let you charge a saved customer again without holding their card, which is what makes subscriptions, one-click checkout and account updates possible without turning your database into a breach target.
The constraint to plan for is that tokens are usually specific to the provider that issued them. Moving processor can mean the saved cards do not come with you unless a vault migration is arranged in advance, so it is worth asking about portability before you have thousands of stored customers.