The basic concept behind patents was laid out by the English parliament in 1623 in an attempt to prohibit monopolies by law. One of the exceptions they allowed was a monopoly grant, good for about 20 years, to anyone who took the risk of bringing a new product to the market, and who publicly disclosed the source of that product so that competition could start as soon as the patent expired. So too today, a utility patent gives the patent owner the right to stop anyone else from practicing the claimed invention, for around 20 years from the filing date, depending on the jurisdiction. After the patent has expired anybody can practice the invention, as patents are not renewable. In return for this limited monopoly the inventor has to disclose the invention in sufficient detail so that anyone who is ordinarily skilled in the relevant art can make use of the invention as disclosed. If an idea has not been developed far enough for the inventor to provide the essential "how to" instructions, it may not be considered patentable.