A neutrino detector is a scientific instrument designed to observe and measure neutrinos, which are tiny, nearly massless particles that rarely interact with matter. These detectors are often located deep underground or underwater to shield them from other particles and cosmic rays that could interfere with measurements. Neutrinos are produced in various processes, such as nuclear reactions in the sun or during supernova explosions. By detecting these elusive particles, scientists can gain insights into fundamental processes in the universe, including the workings of stars and the nature of dark matter.