Short answers, pulled from the story.
Particle physics, also called high-energy physics, is the study of the fundamental particles and forces that constitute matter and radiation. It examines combinations of elementary particles up to the scale of protons and neutrons, while the study of combinations of protons and neutrons is nuclear physics.
The Standard Model, as currently formulated, has 61 elementary particles. These can combine to form composite particles, accounting for the hundreds of other species discovered since the 1960s.
Quarks cannot be observed independently because of color confinement. The interactions between quarks store energy that converts into other particles when the quarks are pulled far enough apart.
On the 4th of July 2012, physicists with the Large Hadron Collider at CERN announced they had found a new particle that behaves similarly to what is expected from the Higgs boson. The Standard Model had predicted its existence.
In the Standard Model, fermions are the matter particles and bosons are the force-carrying particles. Quarks and leptons are fermions with half-integer spin, while bosons such as the photon, gluon, W, Z, and Higgs have integer spin and carry the fundamental interactions.
The reconciliation of gravity with current particle physics theory is not solved, and the graviton remains hypothetical and undetected. Measurements of neutrino mass have provided the first experimental deviations from the Standard Model, since neutrinos do not have mass within it.