New Vegas Script Extender
The New Vegas Script Extender is a plugin and loader system designed by the NVSE team to add a vast array of new functions and allowing the creation of new plugins to essentially "hook" into the game engine.
The NVSE loads via a loader exe.
Examples of plugins created with NVSE include JIP Realistic Weapon Overheating, Lutana NVSE plugin, New Vegas Anti Crash and New Vegas Stutter Remover.
Link to the page where you can download NVSE: http://nvse.silverlock.org/ (Always get the latest version)