Explain it to me like I'm new
An API is the official set of doors another program is allowed to use. It defines exactly what you can ask for and what you get back.
Think of it like
A restaurant menu. You do not walk into the kitchen; you order from the list the kitchen agreed to cook.
What actually happens
Your program sends a request to an address with credentials. The service checks who you are and what you may do, then sends structured data back.
app → request(+token) → API → checks permission → response(data)
Where I encountered it
Every integration I have attempted, most recently the Instagram API.
Next words to meet
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