Yes, tags, and really anything illegally spray painted on public or private surfaces. No problem if the city or a building owner wants to commission or invite graffiti artists.

I spent time in several European cities recently (and in the past), and Zurich was the only place where the amount of graffiti really stood out to me. Maybe there was an expectation that a wealthy city/country wouldn’t have tagging, which made it stand out more. Berlin had a lot of both good street art and tagging, but the tagging seemed more concentrated in specific areas.

The graffiti stood out more to me than billboards, but as an American I’m surely desensitized to billboards.