An API is an agreed way for one program to ask another for data or to trigger an action. A store asks the carrier for a delivery price, a website sends a new lead to the CRM, an accounting tool pulls in orders - all through APIs.
Why it matters
Where there is no API, someone copies data from one sheet to another. That costs time and breeds mistakes. An API connection runs on its own, instantly, at night as well as during the day.
What to watch for
Not every system has an API, and not every API exposes everything you need. Before picking a new tool, check what you can actually get out of it and what request limits apply.
