Stateless apps are those that do not store data from web sessions. This necessitates the stateless HTTP protocol, where the server does not keep data from the previous HTTP request- response session on hand to use in the next server- client session.
Each individual session is executed as if it were the first request-response. Data from a new session does not revert to data from the previous session.
Stateless apps are particularly well suited for rendering static web pages that always have the same content. With a stateless app, when a web page is refreshed, all data is completely reloaded. Previous logins are no longer present; the login process must be performed again.
The situation is different with stateful apps, where certain data from the previously accessed web page continues to be used.