Graffiti can be traced back to the Stone Age. Abstract shapes and animals were painted on stone and caves as a mark of expression
78 BC: Graffiti found in early Roman empire cities like Pompeii with popular themes of sex, wine, money and politics
1940s: Fast forward to the 20th century. 'Kilroy was here' became a symbol of the the US Super-GI during WWII and the Korean War. It showed up everywhere, worldwide
1949: Edward Seymour invents the aerosol spray can
1961: The Berlin Wall was built. On the west side people were free to approach the wall and did so with a colourful commentary
1967: Early writers to emerge in Philadelphia include CORNBREAD and COOL EARL
Graffiti becomes popular in New York with writers tagging their aliases with their street number
1970s: Tags start to appear outside trains. Styles become more unique
1972: Hugo Martinez starts UNITED GRAFFITI ARTISTS, a collective that displays graffiti in galleries for the first time
Graffiti spreads across the US
1980s: Graffiti shows close links with the Hip-Hop and Punk movement
Graffiti becomes a global form of expression with new artists emerging and cities taking on their own style
1982: Henry Chalfant's documentary "Style Wars" documents the rise of the graffiti movement
The Broken Window theory is introduced. It implies that petty vandalism leads to more serious crime. Graffiti is seen in a negative light
1990s: The decline of the USSR and fall of the Iron Curtain means more expression in Eastern Europe
1998: The popularity of the internet allows artists to share their work to a wider audience
2004: Artists like BANKSY change public perception. Graffiti starts selling in galleries again
2006: Influenced by the Internet and Western tourists, graffiti becomes popular in smaller Asian cities.
Present: Graffiti is celebrated around UK in festivals like Super Cans (Southampton), Cans Festival (London) and Upfest (Bristol). In 2014 Empty Walls Festival marks the walls of the Welsh capital
