Client–Server Architecture is a model in which a client sends a request to a server, and the server processes the request and returns a response. The client may be a browser, mobile app, or another service.

How it works

• The user performs an action in an application.
• The client sends a request to the backend.
• The backend validates and processes the request.
• The backend communicates with a database if needed.
• The server returns a response and the client displays the result.

Example: login flow

• Client submits credentials.
• Backend verifies them against stored credential data.
• The application creates an authenticated session or issues a token.
• The client receives the result and loads the user's permitted content

Important components

• Client: initiates requests and displays results.
• Server: processes requests and applies business rules.
• Database: stores and retrieves application data.
• Network: carries requests and responses between systems

Common architectures

• Two-tier: client communicates with a server or data layer.
• Three-tier: presentation, application logic, and data layers are separated.
• Multi-tier: the application is split into additional services or layers.