Barbed wire

Barbed wire (also called barb wire) is a kind of wire that is used to make cheap fences. It has sharp metal points (barbs), which make climbing over it painful.
The first patent in the United States for barbed wire was issued in 1867 to Lucien B. Smith of Kent, Ohio, who is regarded as the inventor. Joseph Glidden of DeKalb, Illinois, received a patent for the modern invention in 1874 after he made his own modifications to previous versions. 
It was first used for controlling cattle and later in trench warfare, and in other places to stop people. Improvements led to the creation of Razor wire, in the 1960's.