Lookup Tables (LUTs) are color presets (or "looks" or "filters") that can be applied to images in one step to color grade them. They were initially used in film-making, but are great to color grade still photos too - to either add mood or create a distinctive style.
This video provides definitional information on LUTs, mentions the benefits of using them (and the benefits of working with them in Photoshop versus other programs), points out Web sources for pre-made LUTs and demonstrates how to: (1) Use pre-made LUTs on still photos, (2) Create and save personalized, custom LUTs, and (3) How to convert custom LUTs to Profiles for use on raw images in Adobe Camera Raw (ACR) & in Photoshop's Camera Raw Filter.