Bose-Einstein condensation is a state of matter that occurs at extremely low temperatures, close to absolute zero. In this state, a group of bosons, which are a type of particle, occupy the same quantum state, allowing them to behave as a single quantum entity. This phenomenon was predicted by Albert Einstein and Satyendra Nath Bose in the early 20th century. When cooled to these temperatures, the particles lose their individual identities and exhibit unique properties, such as superfluidity. This means they can flow without viscosity, leading to fascinating applications in fields like quantum mechanics and condensed matter physics.