Physicists have developed a theory called The Standard Model that explains what the world is and what holds it together. It is a simple and comprehensive theory that explains all the hundreds of particles and complex interactions with only:

6 quarks. 6 leptons. The best-known lepton is the electron. Force carrier particles, like the photon.

All the known matter particles are composites of quarks and leptons, and they interact by exchanging force carrier particles.

Read about it at The Particle Adventure.