How to deal with petabytes of data: the LHC Grid project.

We review the Grid computing system developed by the international community to deal with the petabytes of data coming from the Large Hadron Collider at CERN in Geneva with particular emphasis on the ATLAS experiment and the UK Grid project, GridPP. Although these developments were started over a decade ago, this article explains their continued relevance as part of the 'Big Data' problem and how the Grid has been forerunner of today's cloud computing.