用語集一覧AI・開発
API
読み方：A-P-I
Application Programming Interface. A defined set of rules enabling software systems to communicate with each other. Web APIs (typically REST) allow different applications to exchange data over HTTP. APIs power integrations between modern software systems.
What is an API
An API (Application Programming Interface) is a contract between two software systems specifying how they can communicate. When you check weather on your phone, the app calls a weather service API to retrieve current conditions.
Types of APIs
- • REST API: Uses HTTP methods (GET, POST, PUT, DELETE); most common
- • GraphQL: Flexible queries; client specifies exactly what data it needs
- • gRPC: High-performance binary protocol for service-to-service communication
- • WebSocket: Bidirectional real-time communication
Common API Use Cases
- • Embedding map functionality (Google Maps API)
- • Processing payments (Stripe API)
- • Sending email (SendGrid API)
- • Adding AI capabilities (OpenAI API, Anthropic API)
- • Social media integration (LinkedIn API)
Why APIs Matter
APIs enable composability—building products by combining specialized services rather than rebuilding common functionality from scratch. Modern software products are largely orchestrations of APIs.