What was used before APIs became the standard?

Question

I’m not in the IT sector but I’m beginning to understand the logic behind sending requests and receiving responses for various reasons. What was used before APIs became the standard for communication between systems?

Edit: I understand now that I’ve been in fact asking about REST API.

In: Technology

Answer 1

API is a generic term for the interface between two different programs. There are many standard and even more proprietary APIs. As soon as computers were capable of running multiple programs those programs needed to talk to each other, when networks were introduced, the concept was extended to system level communication. The UNIX command line is probably the oldest API still in active use.