A patent is a right granted by a government entity for [intellectual-property] (IP), which excludes others from using that IP. Use this tag when asking specifically about patentability or patented matters.
A patent is granted to an inventor (or assignee) by a sovereign state for a limited period of time. The invention will be either a novel product or process.
The exclusive rights granted by the patent will vary between countries and jurisdictions. However, in general, the patent prevents others from making or using the patented product or process, though its validity may still be challenged in court.
There is a separate Stack Exchange site for patents: Ask Patents. You might want to consider searching if your question has already been asked there.