Barbed wire is a type of fencing made from twisted metal strands with sharp points, called barbs, spaced along its length. The barbs stick out at angles, making the wire painful to touch or climb over. Farmers use barbed wire to keep livestock like cattle and horses inside their pastures without needing tall, expensive wooden fences. The animals quickly learn that touching the wire hurts, so they stay away from it.

Invented in the 1870s, barbed wire transformed the American West. Before its invention, ranchers needed miles of wooden fence or hired cowboys to constantly watch their herds. Barbed wire was cheap, quick to install, and effective. Within just a few decades, it enclosed millions of acres of open rangeland. This changed the landscape dramatically, ending the era of vast open ranges where cattle could roam freely. Some people called it “the devil's rope” because of how it altered the frontier way of life.

The military also uses barbed wire as a barrier to slow down or stop people from crossing into restricted areas. During wartime, soldiers often string barbed wire in front of their positions as an obstacle, and it can cause serious injuries if someone tries to force their way through.