What is the basic structure of an API?

APIs (Application Programming Interfaces) allow different software systems to communicate with each other. When beginning to use or build APIs, it's helpful to understand their underlying structure.

At a high level, APIs consist of two main components:

The Server

This is the backend system that houses the API logic and data. The server handles API requests and responses. Some common languages/frameworks used to build API servers:

Server code organizes data and functionality into endpoints. Endpoints are URLs that provide access to parts of the dataset or actions you can take.

For example, an endpoint like api.example.com/users might return data on all users, while api.example.com/users/123 would return just user 123.

The Client

This is the application consuming and interacting with the API. Common examples:

The client makes requests to API endpoints, triggering whatever action is defined on the server. Requests can use different methods like GET, POST, PUT, DELETE etc. The server then returns a response.

This request-response cycle is the heart of API communication. Both sides speak in a common language like JSON or XML to share data and instructions.

Example Flow

1. A mobile app (client) sends a GET request to api.example.com/users
2. The API server handles the request and queries the database for user data
3. The server returns a JSON response with the user data
4. The mobile app processes the response to display the users

While simple APIs may just perform CRUD operations, more complex workflows are possible with business logic coded into endpoints.

I hope this gives you an idea of the moving parts that make up APIs! They essentially establish a channel for different systems to share processes and data. As you work more with APIs, the patterns tend to become second nature.