An event every year that begins at 12:00 AM on day 20 of April, repeating indefinitely
April 20th has long been accepted as the de facto cannabis holiday. The symbolism behind 4/20 has been a powerful ally and war cry for activists and supporters of cannabis reform. During times of prohibition, it has given the community cause to come together make some noise. – Leafly
April 20 has become an international counterculture holiday, where people gather to celebrate and consume cannabis. Many such events have a political nature to them, advocating the liberalization and legalization of cannabis. Vivian McPeak, a founder of Seattle’s Hempfest states that 4/20 is “half celebration and half call to action”. Paul Birch calls it a global movement and suggests that one cannot stop events like these.
On that day many marijuana users protest in civil disobedience by gathering in public to smoke at 4:20 pm.
SOURCE: Wikipedia