What is everything in the universe made of? If you break down matter to its smallest components, you would eventually reach particles so small that they can no longer be divided. These particles are called elementary particles, and they are the fundamental building blocks of all matter. While ordinary objects like books, chairs, and even your body are made of atoms, atoms themselves are made up of smaller particles. But what happens if you break down those particles? That’s where the world of elementary particles begins.

Elementary particles are the most basic components of matter. Unlike atoms or molecules, they cannot be broken down into smaller pieces. The field of physics that studies these particles is called particle physics, and it uses huge machines called particle accelerators to smash particles together and study their behavior. Thanks to this research, scientists have discovered that all matter in the universe is made up of two main categories of elementary particles: quarks and leptons. There is also a third category of particles called bosons, which are responsible for carrying the forces of nature, like gravity and electromagnetism.

Let’s start with quarks, which are the building blocks of particles like protons and neutrons. There are six different types of quarks, known as flavors: up, down, charm, strange, top, and bottom. The most common quarks in everyday matter are the up quark and the down quark. Protons are made up of two up quarks and one down quark, while neutrons are made up of two down quarks and one up quark. Quarks are never found alone in nature; they are always "stuck together" in groups, held by a powerful force called the strong nuclear force, which is carried by particles called gluons.

While quarks form protons and neutrons, leptons are different. The most well-known lepton is the electron, the tiny particle that orbits the nucleus of an atom. Electrons play a key role in electricity and chemical bonding. But electrons aren’t the only leptons. There are six types of leptons, just like quarks: the electron, the muon, the tau, and their three associated neutrinos (electron neutrino, muon neutrino, and tau neutrino). Neutrinos are incredibly small, almost massless particles that can pass through most matter without being detected. Trillions of neutrinos pass through your body every second, but you never feel them. Leptons, unlike quarks, can exist on their own.

The third important type of particle is the boson, but bosons are a bit different. They are not the building blocks of matter but the carriers of forces. If you’ve ever learned about the four fundamental forces of nature—gravity, electromagnetism, the strong nuclear force, and the weak nuclear force—then you’ve encountered bosons, even if you didn’t know it. For example, photons are bosons that carry electromagnetic energy, which includes light, radio waves, and X-rays. Gluons are bosons that "glue" quarks together to form protons and neutrons. The W and Z bosons are responsible for the weak nuclear force, which is involved in radioactive decay. Finally, there is the Higgs boson, which was discovered in 2012. The Higgs boson is often called the "God particle" because it helps explain how particles get their mass.

All of these particles—quarks, leptons, and bosons—come together to form the Standard Model of Particle Physics, which is like a "periodic table" for particles. The Standard Model explains how particles interact and how the fundamental forces of nature work. However, it is not a complete theory. For example, it doesn’t explain gravity (which is believed to be carried by a particle called the graviton, although it hasn’t been discovered yet). Physicists are still searching for answers to big questions about the universe, like what dark matter and dark energy are made of.

In summary, elementary particles are the smallest building blocks of the universe. Quarks combine to form protons and neutrons, leptons (like electrons) exist on their own, and bosons carry the fundamental forces of nature. Together, they make up the Standard Model of Particle Physics, which explains much of what we know about matter and energy. However, as scientists continue to explore the universe, new particles and discoveries may challenge what we think we know. This ongoing search for knowledge is what makes particle physics one of the most exciting areas of modern science.