Cosmic rays, high-energy particles from space, are studied in particle astrophysics, linking observational physics with particle physics. They help explore astrophysical phenomena like shock acceleration, transport in space, dark matter, and physics beyond the Standard Model. Cosmic rays originate from various sources, including supernova remnants, and their energy spectrum shows features like the "knee" and "ankle," indicating transitions between galactic and extragalactic sources. High-energy cosmic rays, up to 10^20 eV, are rare but provide insights into extreme astrophysical processes. The GZK cutoff suggests that such particles should be limited to distances of about 50-100 Mpc, but observations have not confirmed this, leading to debates about their sources. Experiments like KASCADE and the Pierre Auger Observatory aim to study cosmic rays and their interactions, providing data on their energy spectrum, composition, and propagation. Cosmic rays also contribute to understanding dark matter and antimatter, with experiments like BESS measuring antiproton fluxes. The study of cosmic rays is crucial for particle astrophysics, connecting it with high-energy physics, cosmology, and astrophysics. Future experiments will further explore cosmic rays, offering new insights into fundamental physics and the universe's structure.Cosmic rays, high-energy particles from space, are studied in particle astrophysics, linking observational physics with particle physics. They help explore astrophysical phenomena like shock acceleration, transport in space, dark matter, and physics beyond the Standard Model. Cosmic rays originate from various sources, including supernova remnants, and their energy spectrum shows features like the "knee" and "ankle," indicating transitions between galactic and extragalactic sources. High-energy cosmic rays, up to 10^20 eV, are rare but provide insights into extreme astrophysical processes. The GZK cutoff suggests that such particles should be limited to distances of about 50-100 Mpc, but observations have not confirmed this, leading to debates about their sources. Experiments like KASCADE and the Pierre Auger Observatory aim to study cosmic rays and their interactions, providing data on their energy spectrum, composition, and propagation. Cosmic rays also contribute to understanding dark matter and antimatter, with experiments like BESS measuring antiproton fluxes. The study of cosmic rays is crucial for particle astrophysics, connecting it with high-energy physics, cosmology, and astrophysics. Future experiments will further explore cosmic rays, offering new insights into fundamental physics and the universe's structure.