The idea of computational and data grid is often explained using the electric power grid example. The electric power grid delivers electric power in a distributed and standardised way. You can use any device that has a standard plug if you are able to connect it to the electric power grid through a standard socket.

In the famous book "The Grid" Ian Foster and Carl Kesselman have explained: "The current status of computation is analogous in some respects to that of electricity around 1910. At that time, electric power generation was possible, and new devices were being devised that depended on electric power, but the need for each user to build and operate a new generator hindered use. The truly revolutionary development was not, in fact, electricity, but the electric power grid and the associated transmission and distribution technologies".

For the scientist the process is looking as follows:
1. The user submits his request, specifying the kind of application he wants to use, the operating system and providing input data.
2. The Grid finds and allocates suitable resources (computing systems, storage facilities) to satisfy the user's request.

3. The Grid monitors request processing and send messages about the status of the fulfilment of the request.
4. Finally, The Grid notifies the user when the results are available and presents them.
As the example shows, the user doesn't have to know which resources he/she is using and where they are. They just get computing power and storage space from the Grid through a standard interface.

Therefore, the Grid delivers computational power on the basis of who needs the power, rather than where the power is located. You can run your job on many computers at once, and choose the machines that best suit your job or the Grid makes it authomatically.

There are great number various grid projects in the world, concerning many areas of sceintific research (space investigation, biology, High Energy Physics, climat research, medical research, mathematic, chemistry, and so on).