Glossary · IT & systems
API (Application Programming Interface)
A fixed agreement that lets software talk to other software. One program sends a request over the internet, the other sends back structured data. Every call has been written out in advance by a developer.
API stands for Application Programming Interface. It is the fixed entry point a system opens up so that other software can request data from it or make something happen in it. Your accounting package, your online shop and your CRMA system for managing customer relationships and sales in one clear overview. almost all have one. Where people work with a screen full of buttons, software works with an API.
How an API works
Most APIs today work over the web. One program sends a secure request over HTTPS to a fixed address, for example to retrieve a customer's outstanding invoices. The other program replies with the data in a structured format, usually JSON. This way of working is called REST. The API itself controls who may make a request, for example with a key or a login.
An API does nothing by itself. A developer writes out every call in advance and decides which request goes out at which moment. That makes an API predictable: it does exactly what was agreed.
From API to integration and AI
When you let two systems talk to each other through their APIs, that is called an integrationThe way systems talk to each other, so you don't have to enter your data twice.. You can read more about it under API / integration. With the arrival of AI agentsAn AI application that doesn't just answer, but takes steps itself to complete a task. It chooses the tools it needs, calls them, looks at the result and decides what the next step is., the API takes on an extra role. An MCP server usually sits on top of an existing API, so that an AI model can use it too. A good API is therefore the foundation for both traditional integrations and AI applications.
