This document provides an introduction and overview of grid computing. It defines grid computing as the collection of computer resources from multiple locations to reach a common goal. Key points include: grids link computing resources from different computers and use middleware to connect users' jobs to these resources; grids allow massive computing power by combining hundreds of computers; potential applications include computational services, data services, and information services; advantages include solving larger problems faster and better resource utilization, while disadvantages include evolving standards and a learning curve.