J.J. Thomson was a British physicist born on December 18, 1856, in Cheetham Hill, England. He is best known for discovering the electron in 1897, which was a groundbreaking finding in the field of atomic physics. His work laid the foundation for modern atomic theory and earned him the Nobel Prize in Physics in 1906. Thomson also developed the plum pudding model of the atom, which proposed that atoms were composed of a positively charged "soup" with negatively charged electrons embedded within it. This model was later replaced by the nuclear model proposed by Ernest Rutherford, but Thomson's contributions significantly advanced our understanding of atomic structure.