They are usually done with a thick black magic marker. Even though tagging falls under the same name as graffiti, tagger's have a totally different concept. Taggers are like graffiti artists, they want to be recognized but not by the community. Taggers tag to be recognized by fellow and rival gang members. These crew members use graffiti to distinguish territory and fellow members of their group.
Taggers are what keep people unclear about the concept of graffiti.
Consent is a major issue to those who participate with graffiti. Young graffiti artists can and should obtain consent from business owners to paint on their walls. This can be a start off point for a profession that is not widely known. As graffiti artists usually show a piece in order to get their name on the streets, this will be a good opportunity for them to have a place to work on freely. This way they will not be breaking the law or be worried about being arrested for vandalism.