Grid computing enables the sharing of hardware and data resources to create a cohesive resource environment for executing distributed applications. Although it has been used within the academic and scientific community for some time, standards, enabling technologies, toolkits, and products are becoming available that allow businesses to use and reap the advantages of Grid computing. As with many emerging technologies, the most used toolkits for creating and managing a grid environment are Globus, GridSim and Nirmod. The Globus is a joint effort on the part of researchers and developers from around the world that are focused on the concept of Grid computing. It's organized around four main activities such as Research, Software tools, Testbeds, Applications. The GridSim toolkit allows modeling and simulation of entities in parallel and distributed computing (PDC) systems-users, applications, resources, and resource brokers (schedulers) for design and evaluation of scheduling algorithms. Nimrod incorporates a distributed scheduling component that can manage the scheduling of individual experiments to idle computers in a local area network and even complex parametric experiments can be defined and run with little programmer effort. In this article, the information and concepts of the Globus, GridSim and Nimrod toolkits are discussed.