Traditional, it is the painting in a private or public wall that can be seen by the public it is usually made from spray paint or roll-on paint. It can be just simple words with the writer’s name or a mural image that is very artistic.
Mosaic, it is a combination of small pieces in order to create a big one.
Street installation, it is the trend today by the street art movement. Traditional graffiti is usually on the wall but street installation uses 3D objects and space to meld with the environment.
Flash mobbing, it is where a large number of people assemble in a public place and perform an unusual action in a short period of time before disappearing entirely.
Video projection, it is where the art is generated from the help of the computer.
Stickers, this is where they use homemade stickers commonly use in a propaganda movement to send their message to the government. It is one of the most common graffiti that is being used today.
There are a lot more kinds of graffiti and it will become even more in the following years.