Distributed Computing is an environment in which a group of independent and geographically dispersed computer systems take part to solve a complex problem, each by solving a part of solution and then combining the result from all computers. These systems are loosely coupled systems coordinately working for a common goal. It can be defined as
A computing system in which services are provided by a pool of computers collaborating over a network .
A computing environment that may involve computers of differing architectures and data representation formats that share data and system resources.
The Basic idea between Grid Computing is to utilize the ideal CPU cycles and storage of million of computer systems across a worldwide network function as a flexible, pervasive, and inexpensive accessible pool that could be harnessed by anyone who needs it, similar to the way power companies and their users share the electrical grid. There are many definitions of the term: Grid computing:
Since 1980, two advances in technology has made distributed computing a more practical idea, computer CPU power and communication bandwidth. The result of these technologies is not only feasible but easy to put together large number of computer systems for solving complex computational power or storage requirements. But the numbers of real distributable applications are still somewhat limited, and the challenges are still significant (standardization, interoperability etc).
As it is clear from the definition, traditional distributed computing can be characterized as a subset of grid computing. some of the differences between these two are
1. Distributed Computing normally refers to managing or pooling the hundreds or thousands of computer systems which individually are more limited in their memory and processing power. On the other hand, grid computing has some extra characteristics. It is concerned to efficient utilization of a pool of heterogeneous systems with optimal workload management utilizing an enterprise's entire computational resources( servers, networks, storage, and information) acting together to create one or more large pools of computing resources. There is no limitation of users, departments or originations in grid computing.
2. Grid computing is focused on the ability to support computation across multiple administrative domains that sets it apart from traditional distributed computing. Grids offer a way of using the information technology resources optimally inside an organization involving virtualization of computing resources. Its concept of support for multiple administrative policies and security authentication and authorization mechanisms enables it to be distributed over a local, metropolitan, or wide-area network.