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

Still APIs. They just used older standards, such as SOAP. Before that they just used non-standard APIs, i.e. each software developer could just create their own communication protocol and use that.