The 960 Grid System is a framework for streamlining web development workflow that is based around a 960 pixel width. It provides commonly used column dimensions of 12 or 16 columns that can be used separately or together. Some benefits include rapid development, clean grid structure, and easy creation of complex layouts. However, it also has limitations such as being restricted to the 960 pixel width. The document discusses the history and features of the 960 Grid System framework.