It allows you to change the order in which the game engine loads plugins and masters to prevent conflicts between mods that may cause glitches or crashes.
LOST, the Load Order Sorting Tool, is a simple and straightforward, leightweight load order manager program for TES IV: Oblivion, Fallout 3 and Fallout New Vegas (you do not need all for it to work), written in the Python programming language. Otherwise, UAC will prevent LOST from accessing the required files. If you are getting errors when starting LOST stating it cannot load the settings, make sure you run the program as an administrator or install the application somewhere outside of your Program Files folder.