Barbed wire is a type of fencing wire constructed with sharp edges or points arranged at intervals along the strand(s). It is used to construct inexpensive fences and also on walls surrounding secured property. Barbed wire was the first wire technology capable of restraining cattle.
Barbed wire fencing requires only fence posts, wire and fixing devices such as staples. It is simple to construct and quick to erect by even an unskilled fencer. 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 posts and battens, or steel star posts.
To prevent humans crossing through or over barbed wire fences, many prisons and other high-security installations construct fences with razor wire, a variant which instead of occasional barbs features near-continuous cutting surfaces sufficient to injure unprotected persons who climb on or over it.