phenoGrid is a collaboration of UK Particle Physics Phenomenologists who are developing applications for the LHC. PhenoGrid is a part of GridPP.
GridPP is a collaboration of Particle Physicists and Computing Scientists from the UK and CERN, who are building a Grid for Particle Physics.
The LCG project, based at CERN, has the job of preparing the computing environment for the analysis of the LHC data. The computing requirements are much greater than could be satisfied at CERN alone, and so a major aim of LCG is to make the Grid work as an effective service for physicists working on LHC analysis.