A tokamak is a device designed to confine and control hot plasma using magnetic fields, aiming to achieve nuclear fusion. It consists of a doughnut-shaped chamber where hydrogen isotopes are heated to extreme temperatures, allowing them to fuse and release energy, similar to processes occurring in the sun. The magnetic fields in a tokamak are generated by powerful electromagnets, which create a stable environment for the plasma. Researchers believe that successful fusion in tokamaks could provide a nearly limitless source of clean energy, making it a significant area of study in nuclear physics and energy production.