GRAFFITI IS no longer an underground activity. It has emerged as an element of pop culture seen in dark subways just as often as art galleries and shopping malls.
Graffiti artists have even been invited to paint for advertising firms and brand name companies.
There are also courses in graffiti and competitions for budding graffiti artists to show off their talent.
But when graffiti first appeared in New York and Philadelphia in the 1960s, street gangs would put their names (called 'tags') on it to mark their territory.
Ethnic minorities would also paint on walls as an act of rebellion against society. People who tag, known as writers, use markers or colourful spray paint to draw stylised letter-forms.
'As an ethnic minority in a suburb, nobody gave us the opportunity to express ourselves. I thought graffiti was a great way to express my creativity and find my own identity,' said graffiti artist John Perello, aka JonOne, who is of Dominican descent. He grew up in Harlem, New York in the 1970s.