The Kondo effect is a phenomenon in condensed matter physics where the electrical resistance of a metal increases with decreasing temperature due to the interactions between conduction electrons and localized magnetic impurities. This effect was first observed in the 1930s by Jun Kondo in his studies of magnetic impurities in metals. The Kondo effect plays a significant role in understanding the behavior of certain materials, such as heavy fermion compounds and quantum dots, and has important implications for fields such as nanotechnology and quantum computing.