High energy physics, or elementary particle physics, is the study of the most basic building blocks of matter. The most familiar such particles, the proton, neutron, and electron make up the matter we see on earth, but there are many other particles which are created only in high energy interactions and decay rapidly to the more familar ones. High energies are also needed to probe the structure of particles like the proton to try to understand the dynamics of the quarks and gluons which make them up.
To study the properties of these particles, and to discover new ones, we must accelerate particles to very high energy and cause them to collide with a fixed target, or head on with a beam of particles traveling in the opposite direction. This generally requires very large apparatus, and so most high energy research is carried out at high energy physics labs around the world.
