API

An API (Application Programming Interface) is an interface that receives and processes requests and returns appropriate results. It consists of defined commands, functions, protocols, and data structures that enable access to systems and their functions.

Functionality and Use

An API acts as an intermediary between applications, enabling them to communicate with one another and exchange data. Developers use APIs to create software or interact with external systems without needing to know the details of how those systems work internally.

A client sends a request to the API, which forwards it to a system or server. There, the data is processed and returned as a structured response, e.g., in JSON format. In doing so, the API ensures that only relevant information is transmitted and internal system details remain hidden.

APIs are used to connect applications and enable the exchange of data and functions. They facilitate the integration of external services and accelerate software development. APIs can be made available internally, to partners, or publicly, and are a central component of modern digital systems.

Types

• Internal API: Used only within a company and not publicly accessible.
• Partner/Customer API: Made available to selected business partners to connect systems across companies.
• Public API: Is freely accessible and allows developers to integrate external services or data into their own applications.
• Composite API: Combines multiple data sources or services and enables access to multiple endpoints via a single request.

Examples

• A weather app retrieves current weather data from an external service via an API
• An online store uses a payment API (e.g., PayPal) to process transactions
• A website allows users to log in via Google or Facebook using an API
• A mapping application integrates services such as Google Maps for navigation via an API