Why is HTTP called a "stateless" protocol?

Each HTTP request is independent and self-contained, so the server keeps no memory of previous requests.

After sending a response, the server has no memory of the client. Each request-response cycle is complete in itself. This means the server can't naturally track:

• Which user is making requests
• What they did in previous requests
• Shopping cart contents, login status, etc.

Cookies and sessions were invented to work around this limitation.