A tagger is a person who writes their name or their special sign on walls, trains, shop shutters, and other places in public, without permission. The name they write is called a tag — usually a short made-up nickname, written fast in one style, over and over in many places. That repetition is the point: a tagger wants to be seen everywhere, so the same tag appears again and again across a city. It is worth knowing how this word sits next to graffiti artist. Graffiti covers everything from a quick scribble to a huge, careful, coloured picture on a wall. Tagging is the quick end of that — a signature, not a picture. So calling someone a tagger, rather than a graffiti artist, usually says something: it suggests speed and name-writing rather than art. Inside that world, some people who paint big pieces look down on plain taggers a little. Outside it, city officials and shopkeepers use tagger plainly for someone doing damage, and it sounds disapproving. The word is normal, everyday English, not slang you need to avoid, but it carries the idea of something illegal. The same word is also used, in totally separate everyday ways, for a person or machine that puts labels or tags on things — for example someone tagging clothes in a shop, or software that tags photos.

塗鴉客、在牆上亂噴（簽）名的人；台灣口語常說「噴漆的」「亂塗鴉的人」