The Standard Model is an enormously successful theory devised to explain how subatomic particles interact with each other. The Standard Model is a quantum field theory. It is effectively the union of quantum chromodynamics and the elecroweak theory.
In the Standard Model, there are 16 fundamental particles – 12 particles of matter and 4 force carrier particles). An additional particle, known as the Higgs boson, must also be included to explain why the other 16 have mass. Particles acquire their mass, it is theorized, through interactions with an all-pervading field, called the Higgs field, which is carried by the Higgs boson.
The Standard Model was developed in the late 1960s and early '70s and has stood up to numerous experimental tests. However, it is generally accepted among physicists that it cannot be a fundamental theory of nature since it fails to include gravity, and doesn't account for the existence of dark matter, dark energy, or neutrino oscillations. Indeed, it only makes sense if viewed as a low-energy approximation.