Graffiti is a form of artistic expression that involves writing or drawing on surfaces without permission. It ranges from simple tags to elaborate murals using spray paint or markers. Graffiti originated thousands of years ago with cave paintings and has evolved over time from being seen as only vandalism to an accepted art form. Popular graffiti styles include tags, throw-ups, blockbusters, and wildstyle which use techniques like stenciling, stickers, and intricate lettering.