The Higgs boson is a hypothetical elementary particle predicted by the Standard Model (SM) of particle physics. It belongs to a class of particles known as bosons, characterized by an integer value of their spin quantum number. The Higgs field is a quantum field with a non-zero value that fills all of space, and explains why fundamental particles such as quarks and electrons have mass. The Higgs boson is an excitation of the Higgs field above its ground state.
The existence of the Higgs boson is predicted by the Standard Model to explain how spontaneous breaking of electroweak symmetry (the Higgs mechanism) takes place in nature, which in turn explains why other elementary particles have mass. Its discovery would further validate the Standard Model as essentially correct, as it is the only elementary particle predicted by the Standard Model that has not yet been observed in particle physics experiments. The Standard Model completely fixes the properties of the Higgs boson, except for its mass. It is expected to have no spin and no electric or color charge, and it interacts with other particles through weak interaction and Yukawa interactions. Alternative sources of the Higgs mechanism that do not need the Higgs boson are also possible and would be considered if the existence of the Higgs boson were ruled out. They are known as Higgsless models.