Can you explain the key principles of RESTful API architecture?

A RESTful API is built on several key principles:

1. Client-server architecture — the client and server are separated, allowing them to evolve independently.

2. Statelessness — each request from the client to the server must contain all the information needed to process it; the server does not store state between requests.

3. Caching — responses can be cached by the client or intermediate nodes to improve performance.

4. Uniform interface — using standard HTTP methods (GET, POST, PUT, DELETE, etc.) and clearly defining resources via URLs.

5. Layered system — architecture can include intermediate servers, proxies, load balancers.

6. Code on demand (optional) — the server can transmit executable code to the client (e.g., scripts), but this is rarely used.

Example:

• Resources are represented as URLs, e.g., /users/123 — user with ID 123.
• GET /users/123 — retrieve user data.
• PUT /users/123 — update user data.
• DELETE /users/123 — delete the user.

Thus, a RESTful API is based on HTTP standards and principles that ensure simplicity, scalability, and component independence.