You probably still think of it as a “cash register” – basically a fancy calculator and cash drawer that sits at the end of the shopping aisle just before the exit, which gives you the correct change on your way out.
Sure, it has a few more flashing lights than a few years ago, but it’s still essentially a machine whose only role in life is to accommodate a transaction every few minutes.
The modern point-of-sale (POS) system is a tightly integrated computer that almost certainly knows all about your buying history, how often you shop online and what you’re likely to buy next week.
It is also able to communicate along the entire length of the store’s supply chain right back to the factory if necessary.
Not bad for a device that has its origins in the late 1800s and was used primarily for producing a simple receipt – one copy for the merchant and one for the costumer.