Hadrons are subatomic particles made up of quarks, which are held together by the strong force. They are classified into two main types: baryons and mesons. Baryons, like protons and neutrons, consist of three quarks, while mesons are made of one quark and one antiquark. Hadrons are a key component of atomic nuclei. These particles are part of the Standard Model of particle physics, which describes the fundamental forces and particles in the universe. Hadrons are not fundamental particles themselves; instead, they are composite particles that play a crucial role in the structure of matter.