A utility patent can cover a process, a method, a machine, an article of manufacture, a composition of matter, or improvements in any of these things.

Several things cannot be patented even if they fall into the above categories including:

• Laws of nature
• Abstract ideals
• Literary works
• Physical phenomena
• Offensive inventions
• Inventions that aren't useful including things considered to violate the laws of science such as perpetual motion machines and perpetual energy generation.