Which of the following knots is not a secure knot by itself and is used in conjunction with other knots?

The half hitch is not considered a secure knot by itself and is typically used in conjunction with other knots to enhance its security. It is primarily utilized to add stability to a knot or to secure the working end of a rope. When used alone, the half hitch can easily come undone or slip under tension, making it unreliable for tasks where security is paramount.

In contrast, the bowline creates a fixed loop that is secure and easy to untie, and the figure eight is known for its reliability and strength as a terminal knot. The clove hitch can be used as a secure binding knot, particularly for mooring or securing items to a post, assuming there is tension present.

Therefore, understanding the half hitch's role in conjunction with secure knots is crucial, as it is primarily used to augment the effectiveness of those more reliable knots. This highlights the importance of knowing not just individual knots, but how they can be used in combination to achieve the desired security and effectiveness in various applications.