A spin-off in television is a new series which contains either characters or theme elements from an old series. They are particularly common in situation comedy.
Television spin-offs come in several variations, including:
A supporting character or characters in an existing series is given their own show in which they become the main focus. The original series continues and there may be some crossover of characters between the shows on occasion (e.g. Angel from Buffy The Vampire Slayer).
New characters are specially incorporated into an existing series for the sole purpose of being launched into their own show that will feature no regular characters from the original series, except possibly as guest appearances (e.g. Empty Nest from The Golden Girls, or Boston Legal from The Practice).
Regular characters from a series continue in their own series after the original series ends (e.g. George and Mildred and Robin's Nest from Man About the House; Frasier from Cheers). This is usually done with the same actors, though not always (e.g. Trapper John, M.D.).
A new series is started with the same theme as an existing series, though not necessarily with the same characters. Examples of this type are the Star Trek, Law & Order, and CSI series. These are sometimes called franchises. The reality showsSurvivor, Big Brother and The Amazing Race also operate in this manner.
One notable case which is not a spin-off is when the same series is later remade. Examples include He-Man and the Masters of the Universe (1983, 2002) and Teenage Mutant Ninja Turtles (1987, 2003).
Many, if not all spinoffs, are produced by some of the original producers of the root show.
The current 'title holder', based on available information, is All In The Family for total number of spinoff series' (7, in 3 generations); there is an 8-way tie for greatest depth of spin-offs (3) (10-way, if you count game shows).
It ran on the NBC network from 1979 to 1988 and was produced first by TAT Communications, then Embassy Television, followed by Embassy Communications, and finally, Columbia Pictures Television (through ELP Communications).
The spinoff focused on Charlotte Rae's character, Edna Garrett, as she became housemother to seven young girls at the Eastland Academy in Peekskill, New York.
The series was given a berth on the 1980-81 American network television schedule, and the show was a constant Top 30 hit for most of the early and mid-1980s.