What is the difference between a session and cookies?

Cookies store data on the client side (in the browser), representing text files with a "key=value" pair and information about their expiration date and domain. They are used to save user preferences, authentication, and activity tracking. The server sends cookies to the client, and the browser automatically sends them back to the server with each request to the corresponding domain.

A session stores data on the server side. The client (browser) receives a unique session identifier (SID), which can be stored in cookies or transmitted via URL. The server associates the SID with a specific set of data (e.g., cart state, authenticated user information). The session ends after a period of inactivity or when the browser is closed (depending on settings).

Comparison table:

Feature	Cookies	Session
Storage location	Client (browser)	Server
Data volume	Limited (usually a few KB)	Unlimited, depends on server resources
Security	Less secure (can be read)	More secure (data on the server)
Management	Server sends, browser stores/sends	Server creates and manages data, browser stores SID
Purpose	Storing small data, preferences	Storing user state, large data