# Unknot

The

**unknot** is a loop of rope without a

knot in it (in

knot theory, ropes have no ends; they are loops). A

knot theorist might describe the unknot as the standard embedding of the

circle (i.e. what the layman would call a circle), though any knot that can be 'untied' to give this would also be considered as the unknot. Deciding if a particular knot is the unknot was a major driving force behind knot invariants and it is not known whether the current invariants are sufficient to answer this question.

This object is also called the **not knot** or the **trivial knot**, the latter is the more natural name for it, since it fits in with the usual mathematical concept of 'trivial', but the punning term **unknot** has stuck. Nevertheless, it is common to say a knot 'is trivial' to mean it is the unknot.

Some useful rope shapes are actually unknots, such as the slip knot and the sheepshank.