Monopoly is a board game published by Parker Brothers, a subsidiary of Hasbro. Players compete to acquire wealth through stylized economic activity involving the buying, renting, and trading of properties using play money, as players take turns moving around the board according to the roll of the dice.

The object of the game is to bankrupt the other players. The game is named after the economic concept of monopoly, the domination of a market by a single entity.

Monopoly is the most commercially-successful board game in history, with 480 million players worldwide.

According to Hasbro, since Charles Darrow patented the game in 1935, approximately 750 million people have played the game, making it "the most played (commercial) board game in the world."

The 1999 Guinness Book of Records cited Hasbro's previous statistic of 500 million people having played Monopoly. Games Magazine has inducted Monopoly into its Hall of Fame.

The history of Monopoly can be traced back to the early 1900s. In 1904, a Quaker woman named Elizabeth (Lizzie) J. Magie Phillips created a game through which she hoped to be able to explain the single tax theory of Henry George (it was supposed to illustrate the negative aspects of concentrating land in private monopolies). Her game, The Landlord's Game, was commercially published a few years later.

Other interested game players redeveloped the game and some made their own sets. Lizzie herself patented a revised edition of the game in 1904, and similar games were published commercially. By the early 1930s, a board game named Monopoly was created much like the version of Monopoly sold by Parker Brothers and its parent companies throughout the rest of the 20th century and into the 21st.

The Parker Brothers' version was created by Charles Darrow. Several people, mostly in the U.S. Midwest and near the U.S. East Coast, contributed to the game's design and evolution.

In 1941 the British Secret Service had John Waddington Ltd., the licensed manufacturer of the game outside the U.S., create a special edition for World War II prisoners of war held by the Nazis. Hidden inside these games were maps, compasses, real money and other objects useful for escaping. They were distributed to prisoners by the International Red Cross.

By the 1970s, the game's early history had been lost (and at least one historian has argued that it was purposely suppressed - see below), and the idea that it had been created solely by Charles Darrow had become popular folklore.

This was stated in the 1974 book The Monopoly Book: Strategy and Tactics of the World's Most Popular Game, by Maxine Brady, and even in the instructions of the game itself. As Professor Ralph Anspach fought Parker Brothers and its then parent company, General Mills, over the trademarks of the Monopoly board game, much of the early history of the game was "rediscovered."

Because of the lengthy court process, and appeals, the legal status of Parker Brothers' trademarks on the game was not settled until the mid-1980s. The game's name remains a registered trademark of Parker Brothers, as do its specific design elements. Parker Brothers' current corporate parent, Hasbro, again acknowledges only the role of Charles Darrow in the creation of the game.

Anspach published a book about his researches, called The Billion Dollar Monopoly Swindle (and republished as Monopolygate), in which he makes his case about the purposeful suppression of the game's early history and development.

The game's official mascot is Rich Uncle Pennybags, who first appeared on the game's Chance and Community Chest cards in 1936. Since 1985, he appears on the second "O" in the word Monopoly as part of the logo. Hasbro officially renamed the character Mr. Monopoly in 1998.

The character of Pennybags is loosely based on American billionaire J. P. Morgan.