Roblox is an online game platform and game creation system that allows users to program games and play games created by other users. Founded by David Baszucki and Erik Cassel in 2004 and officially released in 2006, the platform hosts user-created games in many genres, such as racing games, role-playing games, simulations and obstacle courses, coded in the programming language Lua. Roblox is free-to-play, with in-game purchases available through a virtual currency called "Robux". As of August 2019, Roblox has over 100 million monthly active users. Roblox has received generally positive reviews from critics.

Roblox allows players to buy, sell, and create virtual items (which are worn on avatars). Clothes can be bought by anyone, but only players with a premium membership can sell them. Only Roblox administrators can sell accessories, body parts, gear, and packages under the official Roblox user account; virtual hats and accessories can also be published by a select few users with past experience working with the Roblox Corporation. Items with a limited edition status can only be traded between or sold by users with premium membership status.

Robux is the virtual currency in Roblox that allows players to buy various items. Players can obtain Robux by purchasing it with real currency, from a recurring stipend given to members with premium membership, and from other players by producing and selling virtual content on Roblox.

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