What are Elementary Particles

Elementary particles can be considered to those particles whose subdivision is not possible. Before 20th century, atom was considered the building block of any matter. Further research and experiment showed that even atom were made of electron and nucleus consisting proton and neutron. After a few decades, with advancement of science and technology, it was found that even though electron was an absolute particle , proton and neutron were made of quarks.
One of the most important characteristics of elementary particles is that they are exactly identical in themselves. 

Elementary particles are divided into two groups named as fermions in the name of physicist Enrico Fermi, and bosons , in the name of Indian physicist S N Bose. Fermions  are the building block of the matter whereas bosons are the carriers of forces which have been divided into strong, electromagnetic, weak and gravity. Fermions have been subdivided into quarks and leptons.

 Quarks:

 Quarks are the particles those participate in strong ( nuclear) forces whereas leptons don't participate. For e.g. , three quarks make proton and neutron with the help of strong forces. Fermions are grouped in three generations, each consisting two quarks and two leptons. Well, generations are idea to divide and distinguish the fermions based on masses. Third generation fermions are more massive than second and second generations are more massive than first. Due to their masses, 2nd and 3rd generations fermions have very short lives and very rare in nature. Well, there are six quarks in nature named up, down, charm strange, top and bottom. As already mentioned, quarks participate in strong forces and form larger particles. For e.g. proton is made of two up and one down quarks whereas neutron is made of two down and one up quarks. All quarks carry charges. Up, charm and top take positive charge (+2/3) and down, strange and bottom takes negative charge (-1/3). 

Leptons :

Leptons are the fermions those don't participate in strong forces and don't combine to form other particle. Leptons are named electron, muon, tau and three neutrinos. Electron, muon and tau carry a negative charge (-1) whereas neutrinos have no charge and they are the least reactive with other particles. That is the reason we know least about neutrinos named ghost particle too. Muon and tau can be considered as massive version of electron.

Bosons:

Bosons, as mentioned earlier, are considered  carriers of forces. In nature, forces are divided into strong, electromagnetic, weak and gravity force. For every force, there are v particles which are reasons of arising a force between any pair of particles. For every force there are seperate boson. For e.g. gluons are the boson associated with strong (nuclear) forces. Photon are the particles associated with electromagnetic forces.  There are three boson named weak gauge bosons those are carriers of weak forces. They are represented as W+, W- and Z. They are responsible for radioactive decay of matter and also, in certain conditions, allow proton to convert into neutron and neutron to convert into proton.
Last boson is gravitons which is responsible for gravity force. Even though it has not been detected but it is assumed that there would be a particle which carries this weakest force of nature.