A time-stealing tesuji is a colloquial expression referring to play that forces the opponent to use more time than otherwise necessary with the intention of inducing a mistake or loss on time. Two examples are starting unnecessary or otherwise unwinnable kos and speculative invasions.
Time-stealing tesujies are most effective when the opponent is short on time. However, because they take advantage of game-settings that are external to the intrinsic rules of go they are frequently criticized as unsportsmanlike-like and/or unethical, having been the source of many arguments and discussion in casual and tournament play. As a result, some organizations and tournaments have intentionally made rules against the use of such tactics or ruled against such play in the middle of a tournament.[CitationNeeded]
A move that saves the flag from falling is called a time tesuji, which is to be distinguished from a time-stealing tesuji.