A subatomic particle is any various self-contained unit of matter or energy!

 

The discover, in 1897, of the electron and of the atomic nucleus (in 1911) established that the atom is actually a composite of a cloud of electons surrounding a tiny, but heavy core.  By the early 1930s, scientists had found that the nuclues is composed of even smaller particles (called protons and neutrons).  In the early 1970s it was discovered that these particles are made up of several types of even more basic units named quarks! Quarks and protons/neutrons together (along with several types of leptons), constitute the fundamental building blocks of ALL matter!  A third major group of subatomic particles consists of bosons, which transmit the forces of the universe.  More than 200 subatomic particles have been detected so far, and most appear to have a corresponding antiparticle (like matter and anti-matter).