The document provides an overview of grid computing, including:
1) Grid computing involves sharing distributed computational resources over a network and providing single login access for users. Resources may be owned by different organizations.
2) Examples of current grids discussed include the NSF PACI/NCSA Alliance Grid, the NSF PACI/SDSC NPACI Grid, and the NASA Information Power Grid.
3) The document also discusses various grid middleware tools and projects for using grid resources, such as Globus, Condor, Legion, Harness, and the Internet Backplane Protocol.