T-shirts (formerly known as shirts before the shirts feature was implemented) are a wearable decal visible on the front of an avatar's torso, which will show up in-game and on the avatar's picture on the website. They can be layered over shirts and pants. Most of the time T-shirts are made to run ads, advertise groups, gain donations and game-specific VIP abilities (if the T-shirt is worn), and for a simple look. All users can upload a T-shirt, but only Premium members and Groups can sell T-shirts. However, Roblox removed the need to have premium to sell T-shirts but with a 10 robux fee.
After the release of Shirts and Pants, T-shirts saw a decline in its intended use, and after the release of Developer Products and Game passes, T-shirts were no longer being sold for in-game benefits. (They have, however, been used for minor details such as necklaces or hair extensions.)
Before March 2007, T-shirts could only be sold by Roblox and other Roblox staff, as well as players who heavily contributed to the community (such as MrDoomBringer, who helped maintain the official Roblox Wiki) were rewarded with unreleased character customization features of the time, such as body part colors and T-shirts.
In March 2007, an update was announced in which players could modify their character with T-shirts they created or purchased from others.
In April 2008, Shirts and Pants were fully released; to avoid confusion, the original Shirts feature was renamed to "T-shirts" and could be layered on top of Shirts and Pants. During this time, many users, mainly robosapien626, were raiding the catalog with free T-shirts such as the "tux" trend. The way T-shirts appeared over Shirts and Pants had been considered for changes, but had not been changed in over 10 years.
Over time, T-shirts lost its popularity for aesthetics due to the Shirts and Pants features. They have since been used for serving other purposes, although some methods have since been replaced by modern methods.
A few well-known players run comical ads through T-shirts, usually to promote themselves.
Some T-shirts include a link to the group, so that they are advertised, as Roblox previously did not let groups advertise themselves directly. In February 2011, Roblox allowed groups to be advertised directly, so groups did not need to use T-shirts to advertise.
VIP T-shirts were usually created for extra perks in-games that normal players could not obtain, such as special gear and in-game customization. They have long been replaced by Developer Products and Game passes, since players are not required to wear them in-game (the VIP T-shirt may ruin their appearance).
Some members offer a certain amount of money to have users be drawn on a T-shirt made especially for them.
Before the removal of Tickets, users could exploit the use of T-shirts by selling a T-shirt for 10 Tickets, creating multiple accounts and buying it, earning them 10 Tickets per new account. This no longer works as Tickets were removed in April 2016.