Fundamental particle

A fundamental particle (or elementary particle) the smallest type of subatomic particle. Fundamental particles have no subcomponents i.e. they are not made of any smaller particles. They have no substructure and no physical size. Fundamental particles are, almost by definition, the smallest physical objects in the Universe.

Despite their lack of any physical size, fundamental particles have various important properties that differentiate them from one another. These include their mass, their particle spin and their interaction with various forces (electric charge, for example). Different masses, spins and charges give different fundamental particles different properties. Some make up matter, whilst others are force carriers.

Classification
There are many types of fundamental particles. The two primary subdivisions are matter particles (fermions) and force carrier particles (guage bosons). The main difference between these two types of particle is their spin. Matter particles have a fractional spin (such as 1/3 or 1/2) whereas matter particles have an integer spin (such 1 or 2).

Matter particles interact with each other via forces to build larger structures. Quarks combine with each other to create hadrons, and hadrons combine to make nuclei, which themselves combine with leptons to make atoms.

Force carriers, on the other hand, cannot exist in constant, static relationships with other particles. They are constantly in motion. Their interaction with other particles (both matter particles and force carriers) causes them to change properties and/or move.