In 1977, Milton Glaser's "I Love NY" design was unveiled as part of a new marketing campaign for the state of New York. Inspired by pop art, the iconic heart has become one of the most lucrative T-shirt designs of all time.

As T-shirts transformed into identity platforms, the voice of political protest wasn't far behind. Famed English fashion designer Katharine Hamnett met British Prime Minister Margaret Thatcher at London Fashion Week in 1984; the former wore a shirt that read "85% Don't Want Pershing" – a reference to public opposition to the relocation of US missiles. (Two decades later, in 2003, Hamnett sent models down the catwalk wearing shirts with the slogan: "Stop War, Blair Out" during the Iraq War.)

By the year 2000, the rise of fast fashion meant that more than two billion T-shirts were being sold each year – that's about one for every three people on the planet and that figure has since risen. The endless push for consumerism has driven many designers towards a goal of sustainability.

Technology has started to play a role today – and the textile industry has seen lots of innovation. The first bulletproof T-shirt and another that could block up to 99% of UV rays arrived in 2010. Next, the world's first programmable T-shirt – a collaboration between Ballantine's and wearable tech company CuteCircuit – was born two years later, allowing its wearer to display status updates and more on an LCD screen.