In 2010, Michael Hartl posted an essay called The Tau Manifesto on his personal website. In it, he proposed using the Greek letter tau (τ) to represent that number instead. Hartl argued that an existing symbol like τ would face fewer barriers to adoption than a new symbol like the "three-legged pi." A number of news outlets reported on "Tau Day", a holiday proposed in The Tau Manifesto' for June 28 to honour the number 2π.