The graffiti artist is they come from many different backgrounds, but the

taggers usually they come from a more humble kind of background.

And what they want is all they want is to really just leave their mark in the world,

just put their names and say, I'm here and I exist.

If you see that you don't exist, you don't exist professionally, you don't exist socially.

If you scream or if you die nobody noticed. How do you react to it?

You want to go and put your name where everybody else sees. Most people say, why this guy is doing this because we can read nothing, but these guys do this, show the invisible social problem.

From the BBC World Service, I'm Steve Ergus. This is graffiti, paint and protest.

In part one, street artists led me through Paris and Barcelona.

They showed me bold colourful murals that make political and social statements

pro-equality, pro-human rights, anti-capitalism, anti-war, the messages are clear.

In Brazil, there is a lot of that kind of street arts.

In fact, much of it has actually been legalized, but it's nowhere near as widespread

as a very different, dangerous, illegal style of graffiti tagging that's exploded over the past 30 years across Sao Paulo and Rio de Janeiro.

You're not going to see it on TV during the Olympics, but it's part of what we're going to hear about this week.

The first thing that caught my attention was seeing that it wasn't simply like some scribbling on a wall that actually the

letters they had a harmony or a lack of harmony or they have a composition or they had an attitude or they look almost like

the skeletons of cartoons they took originality seriously

it's Thursday evening and just starting to get dark.

I'm right in the center of Sao Paulo near Prasageh Republica

and I'm approaching a huge group of loud very enthusiastic people.

There must be about two to three hundred.

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