R6

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.

Usage
R6 was the original body type 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 or dies. 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. Also, R6 can fit weld arm scripts and certain animations that would be much harder to do for R15.

Trivia

 * This might be the opposite of R15, as this has less animations than R15.
 * There have been 4 Variations of R6 animations, 2007–08, 2009–13, 2013–14, and 2014+.