An API is a specification of the dialect that computer programs or their components use to exchange data with each other or with the hardware they are running on.
In the old days, if you wanted to communicate with a satellite or a warship, you needed a suite of hardware designed for that specific kind of exchange.
For governments large and small looking to unload old and unused capital goods in exchange for cash, and buyers hoping to get their hands on some serious, if dated, hardware, Government Liquidation is the place to be.