[antonvs]

A function call that's not artificially restricted to return to its caller is equivalent to a goto. See "Lambda: The Ultimate GOTO" by Guy Steele.

A continuation is a value that's passed to a function to tell it where to send its result when it's complete.

In imperative programming languages which invariably have restricted function calls, the continuation that every function receives is the address following the function call. This was just a mistake which the earliest programming languages committed, which has been perpetuated ever since, except in functional languages.