The "overhand knot" is the basis of many other knots. For example, the half-hitch and double-overhand knot.

While double-overhand and half-hitches are very useful, the "vanilla" overhand knot is among the weakest of knots and should be avoided in almost all circumstances. I can't say that I've ever found a good use of the "vanilla" overhand knot.

I'm not a climber. I just happen to have some twine on my often for daily use.