by Vivienne Trulock
Many design principles exist due to human limitations in the following areas:
Users can be classified into different categories.
Different design principles exist when the device is a touchscreen rather than a mouse or keyboard driven system.
Also important to consider is the age of the audience. Adults have different design needs to children.
Not all individuals are equally abled. Inclusive / Accessible Design takes this into account.
Other design principles are simply about applying common sense: