A loop describes the return to a previous activity or step in a process. The process path is therefore repeated to a certain extent. A loop often follows a decision, for example, as a result of controls. In the case of controls, loops mean that reworking is necessary. For example, the password and user name or mail address are checked during login. If one of the two criteria is not correct, the check fails or if the result is negative, it must be corrected. In this example, the correction involves re-entering the login data.