R6 is the default animation rig. R6 means "6 body parts" or "6 joints". Players can enable this body type when customizing their avatar. Game developers can enable whether an avatar uses the R6 rig, R15, and Rthro and its Unlocked Scaling. Despite concerns when R15 was released that R6 would become retired, the Roblox developers announced in multiple blog posts that R6 will always be available to players. 
R6 was the original animation of all players on Roblox. It gives the player a torso, two legs, two arms, and a head. These can be distinguished when a player resets and all the body parts detach from the character. At the time, players would move in a repetitive style, with no height changes to show walking and steps. Unlike later avatar types, R6's arms and legs are not broken into smaller joints and therefore move as one piece. Animation packages and body scaling are incompatible with R6 avatars.
- ↑ ROBLOX Blog, The Future of ROBLOX Avatars, https://blog.roblox.com/2016/03/the-future-of-the-roblox-avatar/
- ↑ ROBLOX Blog, The R15 Avatar is Here!, https://blog.roblox.com/2016/09/the-r15-avatar-is-here/