Graffiti is the illegal spraying of paint, dye, permanent inks or other substances to mark buildings, fences and surfaces open to the public. It is a community problem that drives down business revenue, lowers property values and promotes a view that it is an unsafe community.
Remove graffiti as soon as possible. Graffiti vandals move to another location once their "art" isn't displayed any longer. Graffiti is easier to remove in the first 24 hours as it hasn't been exposed to the elements for too long and hasn't had much of a chance to penetrate into the surface.