April Fools' Day is an annual custom on 1 April consisting of practical jokes and hoaxes. Jokesters often expose their actions by shouting "April Fools!" at the recipient, who becomes the "April fool".

In the UK and countries whose traditions are derived from the UK, a rule has been in place since the 1700s that the April Fools' custom ceases at noon, after which time it is considered bad luck to play pranks. Anyone playing a prank after midday is considered the "April fool" themselves.

In France and French-speaking areas of Switzerland and Canada, the 1 April tradition is often known as "April fish" (poisson d'avril) and involves attempting to attach a paper fish to the victim's back without being noticed. Many newspapers also spread a false story on April Fish Day, and a subtle reference to a fish is sometimes given as a clue to the fact that it is an April Fools' prank.

In 1957, the BBC broadcast a film purporting to show Swiss farmers picking freshly-grown spaghetti, in what they called the Swiss spaghetti harvest. The BBC was soon flooded with requests to purchase a spaghetti plant, forcing them to declare the film a hoax the next day.

In 2016, the ancient tradition of hoaxing and playing practical jokes on the first day of April fell victim to a Chinese government crackdown. According to state news agency Xinhua, the holiday "is not consistent with our cultural tradition, or socialist core values."

April Fools' Day took a hit in 2020 when the coronavirus pandemic sapped pretty much everyone's sense of humor. Many large companies, including Google, the king of April Fools', opted out of that year's shenanigans, with one CNN headline reading "April Fools' Day pranks are not funny right now. Don't do them."

On April 1, 1984, Motown legend Marvin Gaye was fatally shot following an altercation with his father after he intervened in an argument between his parents. Many mistook the story for a prank, including fellow singers Smokey Robinson and Jermaine Jackson, who didn't believe the news until it was confirmed by the police. Al Sharpton during his interview for the VH1 documentary VH1's Most Shocking Moments in Rock & Roll referenced the coincidence of the date when he said that Gaye's death came "like a sick, sad joke to all of us."

Much like the Eskimo has multiple words for "snow", the English have multiple words for "fool", including "noodle", "gob", "gobby", or "noddy".

On April 1, 1996, Taco Bell took out a full-page ad in seven leading U.S. newspapers announcing that the company had purchased the Liberty Bell to "reduce the country's debt" and renamed it the "Taco Liberty Bell". Thousands of outraged customers called Taco Bell headquarters before it was revealed that the story was a hoax. White House Press Secretary Mike McCurry responded that the federal government was also "selling the Lincoln Memorial to Ford Motor Co. and renaming it the Lincoln-Mercury Memorial"

Burger King published a full page ad in USA Today announcing the introduction of a new item to their menu: a "Left-Handed Whopper" specially designed for the 32 million left-handed Americans. The new whopper included the same ingredients as the original Whopper, but the condiments were rotated 180 degrees for the benefit of their left-handed customers. The following day, the company revealed the hoax. They also revealed that thousands of customers had gone into their restaurants to request the new sandwich.