Welcome Back, Kotter follows the life of Gabe Kotter (played by Gabe Kaplan), a former remedial school student who returns to his alma mater, Brooklyn's James Buchanan High School, to teach a group of underachieving, mischievous students known as the "Sweathogs". The Sweathogs are made up of Vinnie Barbarino (played by John Travolta), Freddie "Boom Boom" Washington (Lawrence Hilton-Jacobs), Juan Epstein (Robert Hegyes), and Arnold Horshack (Ron Palillo).
Throughout the series, Kotter uses his own experiences as a former Sweathog to connect with and inspire his students, who often find themselves in trouble with the school administration and each other. The show's humor and heart comes from the interaction between the diverse personalities of the Sweathogs and their teacher, as well as the challenges they face both in the classroom and in their personal lives.
The show became a significant cultural phenomenon in the mid-1970s, with John Travolta's star-making turn as Vinnie Barbarino leading to his eventual film stardom. It also spawned merchandise, including a line of action figures and a board game. Despite its popularity, the show was cancelled in 1979 after four seasons due to declining ratings.