The short answer is: Quarks are made of Strings.
The long answer:
At the beginning of the last century (between 1900-1930) modern theory of atom emerged as a consequence of Rutherford, Bohr and Schrodinger work. It was composed out of electrons, protons and neutrons. Around 1970 collision experiments showed that protons themselves were made up of quarks. A new theory to explain this feature of nature emerged. It was named the string theory, and stated that at the lowest level, all bosons (like the photon) were made of tiny one dimensional strings that are closed or open, and that oscillate in various modes. A few decades later (about 1995) the string theory developed into the superstring theory, which by postulating a supersymmetry between bosons and fermions (like the electron) succeeded to extend the string behavior (tiny oscillating strings) to all elementary particles (including quarks). Like the strings of a piano, every musical note (every mode of vibration) constitutes a different subatomic particle, having a different mass and energy. To produce all the necessary modes of vibration (of a string) that describes all the particles we know it is necessary that the strings vibrate in a 10 dimensional space.
What is beautiful in this theory is that all particles we know (electrons, mesons, quarks, photons, and even new undiscovered particles like gravitons) can be represented by the same elementary strings. Thus the theory is likely to succeed to unify all the fields we know in nature (electromagnetic, gravitational, nuclear weak and nuclear strong) and to be what is named the final theory of physics.
Ahh! That was of great help.
Democritus, a Greek from Thrace, is said to have been the first person to suggest that matter is made of atoms, or small particles which are to small to be seen. He is also said to have suggested that the atoms would be made of even smaller atoms.
Democritus appears to have been correct. Matter is made of the atoms on the periodic chart. Those atoms are made of electrons and a nuclei. The nuclei are made of protons and neutrons, which are made of (if I understand the previous posting) quarks.
If we extrapolate, we should expect to find a particle even smaller than quarks.
Or to paraphrase Aristotle and Stephen Hawking, mayble quarks are made of space itself.
But wait. Matter is made up of Molecules Molecules is made up of atoms, Atoms are made up of protons and neutrons, Protons and neutrons are made up of quarks and gluon, But quarks and gluon are made up of what material?
How it is matter makes quarks?
Aristotle might say: Matter itself.
Well, it's almost one word.
but what are bosons and fermions?
I want the answer in one word or in one sentence. What are quarks made of?