TnL or T&L, short for Transform and Lighting it refers to a hardware feature found on some graphics cards. TnL is separate engines on the GPU that enable extremely high polygon count scenes. With TnL technology some or all of the 3-D information normally processed by the computer processor is processed by the GPU. Transform performance determines how complex objects can be and how many can appear in a scene without sacrificing frame rate. Lighting techniques add to a scene's realism by changing the appearance of objects based on light sources.