The
Standard Model of
particle physics is a theory concerning the
electromagnetic,
weak, and
strong nuclear interactions, as well as classifying all the
subatomic particles known. It was developed throughout the latter half of the 20th century, as a collaborative effort of scientists around the world. The current formulation was finalized in the mid-1970s upon experimental confirmation of the existence of
quarks. Since then, discoveries of the
top quark (1995), the
tau neutrino (2000), and more recently the
Higgs boson (2012), have given further credence to the Standard Model. Because of its success in explaining a wide variety of experimental results, the Standard Model is sometimes regarded as a "theory of almost everything".