According to our current understanding in the field of physics, everything in the universe is composed of elementary particles. These particles are the building blocks of matter and energy. The most fundamental particles that make up ordinary matter are quarks and leptons. Quarks combine to form particles such as protons and neutrons, which are the constituents of atomic nuclei. Electrons are examples of leptons and orbit around atomic nuclei.
However, it's important to note that particles themselves are not the end of the story. The interactions and behavior of these particles are governed by fundamental forces. There are four known fundamental forces: gravity, electromagnetism, the strong nuclear force, and the weak nuclear force. These forces mediate interactions between particles, allowing for the formation of atoms, molecules, and more complex structures.
Additionally, particles and forces are described by quantum mechanics, a branch of physics that deals with the behavior of matter and energy on very small scales. According to quantum theory, particles can also be described as waves, and their properties are governed by probabilities rather than definite values.
It's worth mentioning that our understanding of the fundamental nature of the universe is continuously evolving. There are ongoing scientific research and explorations in fields like particle physics and cosmology that aim to deepen our understanding of the nature of matter and the universe as a whole.