Only Premium subscribers (and Builders Club subscribers before it was replaced) can trade limited items and Robux with other users. However, this option has been discontinued. Users who did not own a credit card could use Rixty, which allowed them to purchase gift cards and use Coinstar machines to change the spare change into Robux. Users with an active Premium membership will receive an additional Robux bonus if they purchase Robux. Robux can also be purchased through a Roblox card, which can be purchased at many stores worldwide physically and online. The ability to purchase Robux through the Roblox Mobile App was released on December 11, 2012. Roblox released the ability to purchase Robux through its website on September 26, 2008.

The usage of the former 'R$' abbreviation was discouraged by Roblox after the icon replacement, most likely because an actual currency, the Brazilian real, uses the same abbreviation. On November 21, 2019, the Robux icon was replaced from the former R$ symbol to a rounded hexagonal shape and the color was changed to gold. An example is the Bobux meme that had been famous back in late 2020. It is used both inside and outside of Roblox culture due to its state as an iconic virtual currency. Memes based on a virtual currency typically mock Robux (as well as other in-game currencies, such as Fortnite's V-Bucks and Minecraft's Minecoins.). Robux has been intertwined with meme culture as well. Robux is known as Roblox's primary currency by the community and staff currently, all paid items within the avatar shop are sold for Robux, including user-created content such as microtransactions and game passes. The Robux name was conceived by Shedletsky, being a portmanteau on 'Roblox' and 'bucks'.

Robux were one of two currencies on the platform alongside Tix, which were removed on April 14, 2016. Robux (formerly stylized as ROBUX and denoted by R$) is the virtual currency used across the Roblox platform. All Roblox gift cards will be redeemable for credit denominated in your local currency. Beginning in April 2023 Roblox credit will no longer be denominated in U.S.

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