Core, also known as gm82core, is a quality of life improvement extension for Game Maker 8.1. It adds a number of helper functions, precise timing, globalvars and utility constants, geometry and math, input, registry, and also some functions imported from studio.
Core is also required for running most of the other extensions in the GM 8.2 family.
Created by renex and Floogle. Contains contributions by Lovey01, cam900, Adamcake, includes parts of High Resolution Timer 2 by Kyle Smith, and contains code from GMLScripts.com - check the License for usage.
More detailed usage information is included in the GM 8.2 manual.