Today is the day when people who smoke cannabis gather together to celebrate it around the world.
April 20, or 4/20 to use American shorthand, is the day in cannabis culture when taking a puff of ganja becomes an unofficial holiday. The high holiday, many have called it.
The reason is that 420 has a peculiar significance within herbal counterculture, the number having become a sort of codeword for those who smoke. Some claim this is because the number 420 refers to a numerical code for marijuana; others claim it's because police once used the number to refere to cannabis offences. Others still believe it's because a group of smokers in days of yore used to meet at 4.20pm.
Whatever the reason, April 20 is now the most hallowed day in the smoker's calendar, a black Friday for the sale of pot and its paraphernalia and a time for the world's puffers and inhalers to come together in a hippy haze.
Here's what people have been saying about the day on Twitter: