A utility patent is the most common form of patent in the U.S.
To qualify for a patent, the invention should be a process or method for producing a tangible result. It should describe a machine, article of manufacture, or composition of matter, or any new and useful improvement to an existing patent. In addition, the invention must be useful, be novel and be non-obvious.
A utility patent remains valid only while maintenance fees are paid on it and for up to 25 years.
Software is patentable, but a Supreme Court ruling on June 19th 2014 clarified the meaning of this. It said that if an idea was not patentable in the first place, then adding ‘implemented on a computer’ does not suddenly make it more patentable. In the words in the opinion, ‘merely requiring generic computer implementation fails to transform that abstract idea into a patent-eligible invention.’ The coding is only a means of turning the concept into something that can execute on a computer and so coding is not patentable.
US Patent and Trademark Office: Process for Obtaining a Utility Patent