Adjustment Lights in After Effects

Using lights as adjustment layers lets you precisely control exposure by controlling which layers are affected by which lights. Chris and Trish Meyer have called these "Adjustment Lights" in their 2008 book Creating Motion Graphics with After Effects (see p. 281).

A few months ago Harry Frank posted a tip on using Adjustment Lights in Trapcode Particular and Lux in in the Red Giant QuickTip series. Here's Eran Stern's presentation from 2009, Adjustment Lights: