What is an API?

Purpose

To explain what an API is and why it is used in software development.

Audience

This document is intended for junior developers or programmers with basic software knowledge who are unfamiliar with APIs.

Definition

An API, or Application Programming Interface, is a structured and predictable way for different software programs to communicate with each other.

How It Works (High-Level)

APIs let one program request information or services from another program, without needing to know its internal implementation. Many types exist, including web APIs, which use HTTP to send requests over the internet.

Why and When to Use an API

APIs are widely used in modern software to connect services, like payment gateways, social media platforms, or mapping services to other apps. They save developers time because they can reuse functionality instead of building it from scratch. Some APIs are public and can be used by anyone, while others are private and used only within an organization.

Key Takeaways

• An API allows software programs to communicate
• APIs let one program request services without knowing internal implementation
• APIs connect external services to applications
• APIs can be public or private