The range of patentable subject matter is very wide.  For United States utility patents, patentable subject matter can include nearly anything that involves or results from a human-caused transformation and that is within any of these 4 broad classes:

• "Process"
  • that is, a novel method of transforming nearly anything
  • the method can involve manufacturing, engineering, chemistry, biology, business, information, or software
  • e.g., an innovative method for transforming iron into steel, or a new method of transforming accounting data into a tax return.
• "Article of Manufacture"
  • that is, a new good resulting from a transformation,
  • e.g., a device, such as an innovative light bulb, mouse trap, or modem
• "Composition of matter"
  • that is, a new material resulting from a transformation,
  • e.g., a new chemical compound, drug, or gene sequence
• "Machine"
  • that is, a novel system for causing a transformation,
  • e.g., an innovative machine for making a new or old device

Within these 4 classes, the U.S. Patent and Trademark Office is required to grant Utility Patents that claim useful, novel, non-obvious subject matter ("concepts") that have been adequately described.

A concept is not considered sufficiently useful if it is merely a law of nature, a physical phenomenon, or too abstract (has no described implementations).  Also, the patent application must identify a beneficial use for the concept (other than acting as, e.g., a boat anchor, paperweight, or research curiosity).

A given patent application's concept is not novel (new) if it was:

• known or used by others in the U.S., or patented or described in a printed publication anywhere in the world, before its conception date by the inventors named in the patent application;
• patented or described in a printed publication anywhere in the world, or in public use or on sale in the U.S., more than one year before the filing date of the given patent application;
• abandoned; or
• invented by someone other than the named inventors.

Generally, the novelty of a concept is determined based on a comparison to what is "taught" by the prior art, which is basically everything that was known (e.g., everything published) before the origination of the concept.

A concept is obvious if, at the time it was conceived, a person having ordinary skill in the art would have known of art-recognized reasons to modify or combine prior art references, considered as a whole, to arrive at the concept.  Thus, although an invention might seem "obvious" from a layperson or engineer's standpoint, US patent law can be rather strict about what must be proven before an invention can be deemed "obvious" from a patent law perspective.

A Patentability Search often can help reveal whether a concept is novel (and sometimes non-obvious)

A patent application's description of a given concept is considered adequate if it empowers a person having ordinary skill in the art to successfully (even if non-optimally) implement that concept, in the best manner known to the inventors on the application's effective filing date, and demonstrates that the inventors actually had the concept in mind.