A spinoff in television is a new series which contains characters from an old series. They are particularly common in situation comedies.
Three main types of television spin-off exist:
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 (eg. Rhoda from The Mary Tyler Moore Show)
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 (eg. Empty Nest[?] from The Golden Girls)
... out with 22.3% under the age of 18, 6.3% from 18 to 24, 31.0% from 25 to 44, 26.9% from 45 to 64, and 13.5% who are 65 years of age or older. The median age is 40 years. ...