They write on almost everything and with anything that they can get their hands on. They write with spray paint, pens, markers and even with scribers which are pens which carve into glass. A good example would be tagging on the middle of the freeways. Hard to reach places make it harder for the anti-graffiti cleaners to paint over their names which means that their name will be there for a while. Although tagging seems destructive it is a way of gaining respect.
Respect seems to be the ultimate goal for taggers.
There are many different styles of tagging. Both styles are territorial which marks an area in which they live in and or run. The taggers usually venture off into other areas other than their own neighborhood. Piecer's deal with the art aspect of graffiti. The thought process seems to be used a lot more in dealing with piece's.