A utility patent is the type of patent that is awarded to inventions that perform useful functions. Most of the patents that are issued are of this variety, and in fact most people who simply use the term "patent" are referring to a utility patent. When one of the other forms of patent are being referenced they are usually referred to not by reference to the term patent, but rather as a "plant patent" or "design patent."
Utility patents can be obtained for a thing (i.e., a product or composition), a method for making a thing, and/or a method for using a thing. Many times the news media will report that something that is quite old or well known has been recently patented. Almost always the old thing has not been patented, but rather a new and patentable method of making the thing or perhaps a new and patentable method for using the thing is what has been patented.
A utility patent, once granted, provides the owner of the patent the right to prevent others from making, using, selling and importing a product that is covered by the utility patent. This right extends for a period of time that is 20 years after the filing date of the patent application. Under some circumstances (i.e., when delay is the fault of the government) this time period may be extended. Extensions are rare, unless the patent covers a pharmaceutical product.