Many, if not all spinoffs, are produced by some of the original producers of the root show.
A remake of a pre-existing show is not a spin-off (e.g. The Battlestar Galactica series of 2003 is not considered to have spun off from the one made in 1978). An exception can be made to series such as The Transformers where the lines of continuity are blurred. If a television pilot was written but never shot, it is not considered a spin-off. When a show undergoes a name change, its successor is considered a spin-off from the original program. For example, Archie Bunker's Place is considered a spin-off from All in the Family.
Some spin-offs are "engineered" that introduce a character to one show just so that that character can anchor a new show (that episode of the original show is often known as a "backdoor pilot"). For example, the character Horatio Caine appeared on one episode of the Las Vegas-based CSI: Crime Scene Investigation before the premiere of CSI: Miami. Shows such as Enterprise and Deadline which have no immediate connection to previous series but are still known to exist within the same fictional sphere are also spin-offs.