I’d start with understanding what APIs are:
What is an API, exactly?
Then I’d encourage people to explore an API observe how it behaves. Swagger’s “Pet Store” demo is a nice simple example and it doubles as a nice introduction to Swagger (which is a tool for automatically generating API documentation but also provides an interface to “try” requests with examples).
Swagger Pet Store demo
If you’re looking for a more complex and typical API, there are lots of publicly available APIs, a list of them is here:
The tricky part with these is that you are having to learn a lot all at once though. So be aware of these topics and learn them one at a time instead of all at once:
- Request verbs (GET, POST, PUT, DELETE)
- HTTP Status codes
- Understanding response bodies
- Constructing request bodies
- Authentication and authorisation
- JSON and XML
- Understanding resources
- What IDs mean and how you can use them
- Understanding data types (integers, strings, floats, etc)
I run a workshop covering all of this so I’m happy to help!