Typically it is in the late afternoon Monday through Thursday, sometimes Friday, usually taking place at some point between 4 PM and 7 PM. This promotion is intended to boost business on what may otherwise be a slow day. In most cases the "happy hour" lasts longer than a single hour.
The idea of drinking before dinner has its roots in the Prohibition era. When the 18th Amendment and the Volstead Act were passed banning alcohol consumption, citizens would host “cocktail hours”, also known as “happy hours”, at a speakeasy (an illegal drinking establishment) before eating at restaurants where alcohol could not be served. Cocktail lounges continued the trend of drinking before dinner. "Happy hour" entered civilian use around 1960, especially after a Saturday Evening Post article in 1959. Happy hour has become a tradition for many workers, white and blue collar alike.
In 1984, the U.S. Military abolished happy hours at military base clubs.
The Canadian province of Alberta created restrictions to Happy Hours that took effect in August 2008. All such promotions must end at 8 PM, and drink prices must conform to the Alberta Gaming and Liquor Commission's minimum price regulations at all times.
Despite the controversy, happy hour still exists around the globe. Today in the United States, "Happy Hour" culture consists largely of junior and mid-level professionals getting together for a drink to unwind after work. In the United Kingdom, the cocktail hour serves a similar purpose, but traditionally begins at 5pm and ends an hour later.