In physics, the electroweak theory presents a unified description of two of the four fundamental forces of nature: electromagnetism and the weak nuclear force. Although these two forces appear very different at everyday low energies, the theory models them as two different aspects of the same force. Above the unification energy on the order of 10¹⁴ GeV, they would merge into a single electroweak force.

Mathematically, the unification is accomplished under an SU(2)×U(1) gauge group. The corresponding gauge bosons are the photon of electromagnetism and the W and Z bosons of the weak force. In the Standard Model, the weak gauge bosons get their mass from the spontaneous symmetry breaking of SU(2)×U(1) caused by the Higgs mechanism.

For contributions to the unification of the weak and electromagnetic interaction between elementary particles Sheldon Glashow, Abdus Salam, and Steven Weinberg were awarded the Nobel Prize in Physics in 1979.