Baryonic matter is the form of matter composed primarily of baryons, which are subatomic particles made up of three quarks. The most common baryons are protons and neutrons, which together form the atomic nuclei of atoms. Thus, baryonic matter includes all normal atomic matter such as stars, planets, and living organisms, essentially everything made of atoms

. In particle physics terms, baryons are fermions that interact via the strong nuclear force, and baryonic matter excludes leptons like electrons and neutrinos, even though electrons accompany baryons in atoms. In astronomy, however, the term "baryonic matter" is often used more loosely to refer to all ordinary matter that makes up visible objects, including the electrons, since their mass contribution is very small

. Examples of baryonic matter include:

• Atomic nuclei (protons and neutrons)
• Stars and planets
• Gas clouds primarily made of hydrogen and helium
• Comets, asteroids, and other ordinary matter objects

Baryonic matter contrasts with non-baryonic matter, which includes dark matter and other particles not made of baryons. While baryonic matter makes up all the visible matter in the universe, it constitutes only a small fraction of the total matter-energy content, with dark matter and dark energy dominating the cosmos

. In summary, baryonic matter is the "normal" matter composed of protons and neutrons forming atoms, which constitute the familiar material objects in the universe