Processes form an integral part of any web application. It deals with the flow of information and the conditions that determine the behavior and the route of any application. Processes in Joget is rather like building a flowchart that will contain the roles involved (participants), the activities, the conditions and its executions as well as the data that carries from activity to activity (workflow variables).
Note however that while processes are important, they're not necessarily a must have in a web application. In Joget, its perfectly possible to build a full and complete application in which there are no processes involved.