Non-repudiation

Non-repudiation is when you provide reassurance that an action has taken place. As a typical example, let's say it's lunchtime and you decide to head out of your office to buy lunch at a nearby restaurant. When you pay for your meal, the cashier issues you a receipt. The receipt usually contains the time, location, items purchased, the person who received the payment, and so on. The receipt/bill ensures and proves that the transaction took place.