The so-called "God particle" is more properly known as the Higgs boson. This particle was isolated for the first time at the Large Hadron Collider in a discovery announced on July 4, 2012. According to HowStuffWorks, this particle is fundamentally responsible for giving other particles their mass and might be responsible for the effects of gravity.
The standard model of quantum physics describes objects as having mass not as an intrinsic property, but as a result of passing through a field that imbues them with mass and causes them to behave as if they were attached to weights. This field is known as the Higgs field, after one of its chief theorists, and the Higgs boson is the particle associated with emitting it. In this model, according to HowStuffWorks, photons are free to pass unhindered by the Higgs field, as they do not interact with Higgs bosons, and are therefore massless. Heavy matter, such as protons and neutrons, does interact with the Higgs field, and their interactions have the effect of imbuing the particles with mass. Acquiring mass makes particles susceptible to gravity, and it is hoped that the discovery of the long-suspected Higgs boson helps to unify gravity with the other fundamental forces of the universe.