Short answers, pulled from the story.
The Standard Model is a grand theory describing three of the four fundamental forces and classifying all known elementary particles. It reached its modern form in the mid-1970s when the existence of quarks was finally confirmed.
Physicists including Paul Dirac, Yang Chen-Ning, Robert Mills, Chien-Shiung Wu, Sheldon Glashow, Murray Gell-Mann, George Zweig, Steven Weinberg, and Abdus Salam developed the Standard Model. Key milestones include Dirac's 1928 equation, the 1954 gauge theory extension, the 1961 electroweak combination, and the 1967 incorporation of the Higgs mechanism.
The Standard Model contains 12 elementary particles known as fermions divided into quarks and leptons. These particles are organized into three generations that increase in mass, with the first generation making up ordinary matter and the second and third generations existing only in high-energy environments.
The Standard Model explains fundamental forces through the exchange of gauge bosons that act as messengers between matter particles. Photons mediate the electromagnetic force, gluons mediate the strong interaction, and W and Z bosons mediate the weak interaction.
The Standard Model fails to explain gravity, dark matter, dark energy, and the matter-antimatter asymmetry. It also does not incorporate neutrino oscillations or provide a viable dark matter particle with all required properties.
The Higgs boson was discovered in 2012 at the Large Hadron Collider. It confirms the existence of the Higgs field which permeates the universe and gives particles their mass through interaction.