Happy Days was an American sitcom that aired from 1974 to 1984 on ABC.

Set in Milwaukee, Wisconsin, Happy Days initially revolved around the life and times of Richie Cunningham (Ron Howard), his friends and family during an idealized 1950s and 1960s.

Richie, and his friends Potsie Weber (Anson Williams) and Ralph Malph (Donny Most), anchored the show at the beginning, surviving adolescent life with the help of Arthur "Fonzie" Fonzarelli (Henry Winkler), who was originally a minor character.

The charismatic Fonzie, who attracted women with a snap of his finger, and turned on jukeboxes with a hit of his fist, became so popular with fans that he was given more screen time, and eventually became its central character once Richie left for college.

During the fifth season of Happy Days, an infamous storyline where Fonzie had to jump over a shark on water skis had been noted by some viewers as the start of the the show's decline.

Though some argue that decline originally started with Ron Howard's departure, or when Fonzie's younger cousin Cachi (Scott Baio) was introduced, the term "jump the shark" has since been used to denote the point where a television show passes its peak, turning to extraordinary or desperate storylines to retain viewers.

• Note: Thelinks in this timeline are to IMDb, which has pop-ups.

• 1976: Laverne and Shirley

• 1977: Blansky's Beauties

• 1978: Mork and Mindy

• 1980: The Fonz and the Happy Days Gang animated series

• 1982: Joanie Loves Chachi