What I know about graffiti

I would like to tell you what I know about graffiti so far.
I learned about graffiti during class when I was in primary school. My teacher taught me what graffiti was and introduced us some of the famous graffiti artists and their works, such as Banksy. She also showed us a site where you could design your own graffiti. But because the teacher was only showing the positive side of graffiti, I actually never had much bad impression on it. I used to live abroad and although we don't see much in Japan, graffiti is quite common in Europe.
However, as I make a research about it, I found out that it is illegal in some places and therefore towns are made to spend a lot of money removing it. Also, I learned that because some graffiti artists draw on traffic signs it's confusing the drivers, causing danger. I now understand that graffiti is a controversial issue. I could understand both for and against opinions for graffiti, so I hope I could post lots of information and opinions seen from various points of view through this blog!