They protect only the form in which an idea is fixed, not the substance of an idea, which lies in the territory of patent protection. The obligation extends to the patent applicant or holder as well as accused infringers. The doctrine of equivalence tends to favor the patentee, but this tendency is balanced out by use of prosecution history estoppel . Infringement can occur with or without the accused's knowledge of the patent. In patent cases, these prohibited actions are making, using, selling, offering for sale, or importing into the U.S. a patented invention.
Licenses can extend for the entire length of the patent or for shorter periods of time.
A patent is a government-sponsored monopoly, designed to reward the inventor by providing him with incentive to risk time, effort, and money in developing new technologies. If, during the examination of a patent by the PTO in the course of the issuance process, the patentee had to change his or her claims to avoid existing prior art and avoid a rejection of his application as not novel, the pantentee is held to those new limitations for the rest of the life of the patent. The patentee can't go back later to the original, broader claims. This is a confusing concept, so here's a silly example. Trademark rights may be used to prevent others from using a confusingly similar mark, but not to prevent others from making the same goods or from selling the same goods or services under a clearly different mark.