420

420 is a term associated with cannabis culture and is used as both a code and a calendar date. The most commonly cited origin traces to 1971 in San Rafael, California, where a group of high school students at Marin County's San Rafael High School known as the Waldos used "4:20" as a code word for marijuana. After football practice, they would meet at 4:20 p.m. to search for a rumored cannabis crop, and "4:20" became shorthand for marijuana among the group. The term spread through their circle and was later popularized by supporters of cannabis activism and media, particularly in the 1990s.

Over time, 4:20 evolved into a broader cultural symbol. April 20 (4/20) became an annual date for cannabis celebrations and demonstrations in many countries. Public gatherings, private rituals, and online communities mark the occasion, with activities ranging from casual smoking to concerts and activism aimed at changes in drug policy. The exact meanings can vary by region, from light social use to more organized political advocacy.

Legal status of cannabis varies by jurisdiction, with some places permitting medical or recreational use, others maintaining strict prohibition, and many regions implementing age limits and other regulations. The term 420 remains in common usage within cannabis culture, appearing in media, products, and event naming, even as jurisdictions' policies continue to evolve. As such, 420 occupies a defined niche within modern drug culture and policy debates.