Many people know that barbed wire is sharp ,hard and strong. It is widely used in the military field because it is an inexpensive and effective method to defense the enemy. Bobbed wire is a major feature of the fortifications in trench warfare (as a wire obstacle).But it is not popular in military ,it is also available for civil use.

Barbed wire fences remain the standard fencing technology for enclosing cattle in many countries, but not all. The wire is aligned under tension between heavy, braced, fence posts (strainer posts) and then held at the correct height by being attached to wooden or steel fence posts, and/or with battens in between.
 
Barbed wire for agricultural fencing is typically available in two varieties: soft or mild-steel wire and high-tensile. Both types are galvanized for longevity. High-tensile wire is made with thinner but higher-strength steel. Its greater strength makes fences longer lasting because it resists stretching and loosening better, coping with expansion and contraction caused by heat and animal pressure by stretching and relaxing within wider elastic limits. It also supports longer spans, but because of its elastic (springy) nature it is harder to handle and somewhat dangerous for inexperienced fencers. Soft wire is much easier to work but is less durable and only suitable for short spans such as repairs and gates, where it is less likely to tangle.