It isn't enough to simply accept credit cards as a form of payment; you need the instrumentation that goes along with it. Terminals come in all shapes and sizes, many of them a great deal smaller than they used to be thanks to technological advancement. But regardless of their style, they each have a terminal identification number. Typically eight characters in length, no two TINs are alike, as they must be unique to the terminal in question. TINs - also known as TIDs - allow merchant account providers the ability to track how many transactions occur at any given time. Every POS system comes with a TIN, be it pay-at-the-table, contactless or swiping stations.