API

An Application Programming Interface (API) is a set of defined rules and protocols that allows different software applications to communicate with each other. It acts as an intermediary, enabling a client (such as a mobile app or web browser) to request data or functionality from a server, and the server to return the requested response.

• Endpoints: Specific digital locations or URLs where requests can be sent to interact with an API resource.
• Requests and Responses: The client sends an HTTP request (containing methods like GET, POST, PUT, or DELETE), and the server replies with an HTTP response (typically formatted as JSON or XML).
• Statelessness: Most modern web APIs (like REST APIs) are stateless, meaning each request from a client must contain all the information necessary for the server to understand and process it.

Common Types of APIs

• REST (Representational State Transfer): Uses standard HTTP methods and is widely used for web services due to its lightweight and scalable nature.
• GraphQL: An API query language that allows clients to request precisely the data they need, reducing over-fetching or under-fetching.
• SOAP (Simple Object Access Protocol): A protocol-based approach that relies heavily on XML and strict security standards, often found in enterprise or financial systems.
• Webhooks: Often referred to as "reverse APIs," these allow a server to send real-time data to a client automatically when a specific event occurs, rather than waiting for a request.