A Salesforce approval process is a set of rules that sends a record to the right person for sign-off, locks it while that person decides, and then runs actions for an approval, a rejection or a recall. Think of the signature sheet clipped to a purchase order, except Salesforce routes the sheet and keeps the history.
It matters as soon as your sales team quotes big deals. We built one in our Winter ’27 Developer Edition org: any opportunity of $100,000 or more goes to a sales director, stays locked, and moves to Negotiation/Review once approved. You will see how the parts connect, how to create one with either wizard, how to submit records by button, Flow or Apex, and the three errors we hit.