• describes all experiments on matter and forces
• 
  in the universe (except for gravity)
• explains hundreds of particles
• 
  complex interactions
  in terms of fundamental particles and interactions

Matter Particles:
composites of more fundamental particles
leptons (electrons etc.) and quarks
       ...fermions ...spin 1/2 particles

Force Carrier Particles:
each fundamental interaction
"carried" by a force-carrier particle: photons, etc.
       ...bosons ...spin 0, 1, 2

...see periodic chart of bosons and fermions