Web & SaaS
What is API (Application Programming Interface)?
Definition
A defined contract that allows software systems to communicate with each other — enabling one application to request data or trigger actions in another.
In more detail
An API (Application Programming Interface) is a defined contract that allows one software system to request data or trigger actions in another. APIs enable software components to communicate without needing to know how each other works internally — only what requests they accept and what responses they return.
REST APIs (using HTTP) are the most common type in web development. When your browser loads a product page and the price updates in real time, it's likely using an API call to fetch the latest data. When an AI agent searches the web or reads a file, it's using APIs to interact with those systems.
API keys are credentials that authenticate requests — they should be kept secret (never committed to public code repositories) and rotated regularly. Rate limits restrict how many requests you can make in a given time period, which matters when designing AI workflows that might need to make many calls to external services.
Why it matters
APIs are the connective tissue of modern software. Understanding them helps business leaders evaluate integration possibilities and avoid vendor lock-in when building or buying software.
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