A web application combines browser documents with server-side behavior through HTTP. The browser and server have different responsibilities and communicate through explicit requests and responses.

Browser and server

The browser presents HTML, applies CSS and may execute client-side JavaScript.

The server receives HTTP requests, applies application logic and returns responses such as complete pages, HTML fragments or structured data.

Routes

A server commonly maps HTTP methods and URL paths to application handlers:

GET  /articles/42   → show article
POST /articles      → create article

The route identifies the requested application operation; the handler decides what data and response are appropriate.

Static and dynamic resources

A static resource can be returned largely unchanged from stored content. A dynamic response is produced from current application state, user input, database data or other computations.

State

HTTP itself is request-response oriented, but applications often need state across requests. Sessions, signed tokens, database records and URLs are different ways of representing or referring to that state.

Trust boundaries

Data arriving from the browser is input from another system and must be validated on the server before being trusted for authorization, persistence or other protected actions.

Client-side checks improve interaction but cannot replace server-side enforcement.

Web architecture is therefore an arrangement of responsibilities across a network boundary, not simply a collection of HTML pages with a server attached.