A patent is a right granted for any device, substance, method or process which is new, inventive and useful.
A patent is legally enforceable and gives the owner the exclusive right to commercially exploit the invention for the life of the patent. This is not automatic-you must apply for a patent to obtain exclusive rights to exploit your invention.
Patents give effective protection if you have invented new technology that will lead to a product, composition or process with significant long-term commercial gain.
In return, patent applicants must share their know-how by providing a full description of how their invention works. This information becomes public and can provide the basis for further research by others.
You cannot patent artistic creations, mathematical models, plans, schemes or other purely mental processes.