What are cookies and who creates them?

Cookies are small pieces of data that a web server sends to the browser and that the browser stores on the user's side. They are used to store session information, user preferences, and other data necessary for the proper functioning of the website.

Cookies are created by the server in response to an HTTP request by setting the Set-Cookie header. Cookies can also be created and modified using JavaScript on the client side.

Example of setting a cookie on the server:

HTTP/1.1 200 OK
Set-Cookie: sessionId=abc123; Path=/; HttpOnly

Thus, cookies help maintain state between requests, for example, for authentication or interface personalization.