From the designer:
TAG stands for Tom's Adventure Gaming. This system is based on a set of rules that I put together during my time in the U.S. Army. It was specifically designed to fit in a cargo pocket-sized notebook to allow for role-playing sessions "out in the field." My original design was heavily influenced by Ken St. Andre and his "keep it simple" principle but, over the years, I have continued to make and refine my own rules matrix.
Today, TAG has become a fairly coherent and smooth-running system, requiring only a smallish, portable book, six-sided dice, and a few friends to get a great RPG session going.