Supports and options to increase adhesion are used in oddly shaped parts that would otherwise defy gravity to create a scaffolding from the layers to be placed one on top of the other. These forms of supports can and should be removed after printing, which causes some part post processing to take place.
The parts should ideally be made without the needs for supports, the can even be orientated in certain way in order to reduce or completely remove the need for supports.
An example of a part that was not meant to be printed in this orientation, needing many more additional hours of printing
Now lets see it in the correct orientation
A good way to avoid supports if permitted is to have larger than 45 degree angles overhangs, anything less and the printer will struggle to create the part without supports.
Just as infills have patterns/geometries to choose form so do supports, a number of them will do just fine, however look out for geometries with lines that are to straight or narrow. While cooling parts with very straight geomtries tend to cool rapidly and deform