CHEOPS (Characterizing Exoplanet Satellite) is a European Space Agency (ESA) mission dedicated to studying exoplanets, which are planets outside our solar system. Launched in December 2019, CHEOPS focuses on precisely measuring the size of known exoplanets by observing the transits of these planets across their host stars. By accurately determining the radii of exoplanets and combining this data with existing information about their masses, CHEOPS helps scientists to better understand the composition, structure, and formation of these distant worlds. The satellite is equipped with a single, highly sensitive photometer that captures minute variations in starlight caused by transiting exoplanets. CHEOPS targets bright and nearby stars, allowing for detailed follow-up studies with ground-based and other space telescopes. The mission is a collaborative effort involving ESA, various European countries, and numerous research institutions, and it plays a vital role in advancing our knowledge of exoplanetary systems and the potential for habitable worlds beyond our own.