Three Big Things:
1. Barbed wire became the fencing of choice in the west after the Civil War. It was relatively cheap, withstood a wide range of conditions, and held back the biggest, most stubborn livestock.
2. Barbed wire favored homesteaders moving west, who tended to be small farmers. It threatened, and eventually helped destroy, the mythical “open range” and cowboy culture.
3. Barbed wire is rarely asked about specifically in history standards; it’s central to a wide variety of stuff that is, however.