What is the Higgs boson?

The Higgs boson is a theoretical particle proposed by Scottish physicist Peter Higgs as part of the Standard Model of particles and forces. The Standard Model is an incomplete theory that describes how the 12 known fundamental particles and three of the four known forces in the universe fit together (it doesn’t account for gravity).
According to this theory, many fundamental particles had no mass immediately following the Big Bang, but gained mass later from interacting with an invisible energy field called the Higgs field, by way of a particle called the Higgs boson.
The Higgs boson is one of several missing pieces that make the Standard Model incomplete. Finding it with the Large Hadron Collider would lend additional credence to the Standard Model, giving us a strong indication of the nature of matter. Not finding it, after extensive searching, would indicate this theory is wrong, spurring physicists to focus on other schools of thought.