Drag and Drop is a Windows method to communicate with the program. An element on the screen (e.g. a guest number) can be added to another place by clicking the left mouse button, remain it pressed, shifting the mouse to the respective place (Drag) and then letting go of the button again (Drop). Please see the single Program Descriptions to find out when Drag and Drop is possible.
When clicking on a field capable of Drag and Drop, the mouse pointer changes (e.g. into a hand), when shifting the mouse pointer to another place it turns into a fist and on places where the mouse button can be released again it turns into a pointing hand.