Object
From Sonic Retro
An object is an element in a video game which interacts with the environment (or level) and other objects, and is controlled by simple algorithms and complex subroutines. Objects alter values in the RAM (especially the object's own object RAM) to effect gameplay, and are often represented on-screen by sprites. Sometimes objects are invisible during the game, as is the case for plane-switching tags and lava tags. In Sonic games, the most complex object is always Sonic himself. He is required to be controlled by the player, interact with dozens of other objects, be affected by the curvature and elevation of the floor, and change graphics loaded into the VRAM according to his current behaviour. Sonic is always by far the largest object, in terms of lines of code (and therefore space in the ROM).