A patent war is when two companies argue over who has the right to use a particular invention or product. Companies do this to protect their ideas and make sure no one else is using them. They might file a lawsuit, or they might both apply to the government for a patent. A patent is a kind of official permission that says only the company with the patent can make or use the invention or product. So, a patent war is a legal fight to see who has the right to use a product or invention.