API (Application Programming Interface)

An API is a set of rules and protocols that allows different software applications to communicate and exchange data with each other. It acts as an intermediary, defining the methods and data formats that applications can use to request and receive information. APIs are essential for modern software, enabling systems to integrate and share functionality without needing to know the internal workings of the other.

Example: A mobile banking app needs to verify a user's login credentials. Instead of directly accessing the bank's main database, the app sends a request to the bank's login API. The API receives the request, processes the username and password, and sends back a response to the app. This response might be a "success" message with a secure token, or an "error" message if the credentials were wrong. The API ensures this data exchange is standardized and secure, protecting the bank's internal systems.