Electroweak theory is a fundamental framework in particle physics that unifies two of the four known fundamental forces: the electromagnetic force and the weak nuclear force. Developed in the 1970s by physicists Sheldon Glashow, Abdus Salam, and Steven Weinberg, this theory describes how these forces can be seen as different manifestations of a single force at high energy levels. In electroweak theory, particles called gauge bosons mediate the interactions. The photon is responsible for the electromagnetic force, while the W and Z bosons mediate the weak force. This unification is a key aspect of the Standard Model of particle physics, which explains how fundamental particles interact and form the universe's structure.