Tension wire is an important component when installing fence in yards and is not only used for deer fencing. Tension wire, also known as monofilament wire, is used to make fence mesh taut and to eliminate sagging from post to post.
Fence tension wire is used by [fruit] tree growers and on areas with heavy wind gusts. If tree branches or limbs fall off trees, then the potential to destroy the fence is present without tension wire.
Being that tensioning wire strengthens the top of fences, it is also a barrier between domestic animals and external predators. Having a tight fence at the top will block jumping attempts by wild animals, such as deer and coyotes, and will keep children, pets and gardens secure from the unknown.