A patent is a right to use a certain invention exclusively for a limited period (usually 20 years). The owner of the patent does not 'own' the objects that make up the invention, like an author who has copyrights on a novel does not own the novel bought at a bookshop. Patents prevent piracy of technology in a way that copyright does for literature and music.

In return for these exclusive rights the patentee must make open the details of his invention (so detailed, that someone else is in principle able to copy the result). Others can use this knowledge for further research and, when the patent period is over, use the knowledge for commercial purposes. Without patents, scientists and companies would keep scientific information for themselves. Now they are protected somehow, they can speak out and exchange information with other scientists. This encourages research.

Before a patent can be granted to an innovation, it has to filful the conditions of patentability:

1. It has to be patentable. This is called: statutory subject matter. E.g. life can not be patented. People can not be patented. Patent laws do not permit this.
2. It has to be novel. Only if you are the first to invent, and if the novelty has not been published yet, you can get a patent. In e.g. the U.S. patent law is different on this aspect: there you have to be the first to file a novel thing.
3. It has to be an invention and not a discovery. See question 3.
4. There has to be industrial application. You have to mention the industrial applications in the patent.
5. You have to open your invention to others. This is called disclosure.
6. You have to be clear. You have to give such a detailed description of your invention that a person skilled in the art can conceive what you write in the patent.