Paint
Paints are essential to many traditional games as many use models as part of their games. Some games have models that come unpainted and so must be coated them in whatever combination, however artful or bizarre you like before you can play them.
Most tg makers make their own paints as well, 'official' paints to be used on their models which they recommend, although in practice a number of suppliers make paints of a better quality then others and wise people quickly find out the best ones for the jobs.
Some like GW creates huge paint ranges that frankly become insane, minor variations only someone with an equally insane eye could bother to tell the difference.
There are many terms and techniques associated with paints and modelling painting and many neckbeards will have long experience and equally long advice in telling you just how to get that shade of dwarf flesh just right.