Under the patent statute, any person who “invents or discovers any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof, may obtain a patent,” subject to the conditions and requirements of the law. The word “process” is defined by law as a process, act, or method, and primarily includes industrial or technical processes. The term “machine” used in the statute is self-explanatory. The term “manufacture” refers to articles that are made, and includes all manufactured articles. The term “composition of matter” relates to chemical compositions and may include mixtures of ingredients as well as new chemical compounds. These classes of subject matter taken together include practically everything that is made by man and the processes for making the products.
 
The subject matter of the patent application must be “useful.”, i.e., it must have a useful purpose and also includes operability, since a machine that will not operate to perform the intended purpose would not be called useful, and therefore would not be granted a patent.
 
Courts have held that the laws of nature, physical phenomena, and abstract ideas are not patentable subject matter. A patent cannot be obtained upon a mere idea or suggestion. The patent is granted upon the new machine, manufacture, etc., as has been said, and not upon the idea or suggestion of the new machine. A complete description of the actual machine or other subject matter for which a patent is sought is required.
 
Novelty and Non-Obviousness Requirements
In order for an invention to be patentable, it must be new as defined in the patent law, which provides that an invention cannot be patented if:
“(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention” or
“(2) the claimed invention was described in a patent … or in an application for patent published or deemed published in the US, in which the patent or application,… names another inventor and was effectively filed before the effective filing date of the claimed invention.”
 
An exception may apply to a “disclosure made one year or less before the effective filing date of the claimed invention,” but only if “the disclosure was made by the inventor or joint inventor or by another who obtained the subject matter disclosed… from the inventor or a joint inventor.”
 
The term “otherwise available to the public” refers to other types of disclosures of the claimed invention such as, for example, an oral presentation at a scientific meeting, a demonstration at a trade show, a lecture or speech, a statement made on a radio talk show, a YouTube™ video, or a website or other online material.

The term "effective filing date of the claimed invention" appears in patent prohibitions (1) and (2). For a U.S. nonprovisional patent application that is the first application containing the claimed subject matter, the term “effective filing date of the claimed invention” means the actual filing date of the U.S. nonprovisional patent application. For a U.S. nonprovisional application that claims the benefit of a corresponding prior-filed U.S. provisional application, “effective filing date of the claimed invention” can be the filing date of the prior-filed provisional application provided the provisional application sufficiently describes the claimed invention. Similarly, for a U.S. nonprovisional application that is a continuation or division of a prior-filed U.S. nonprovisional application, “effective filing date of the claimed invention” can be the filing date of the prior filed nonprovisional application that sufficiently describes the claimed invention. Finally, “effective filing date of the claimed invention” may be the filing date of a prior-filed foreign patent application to which foreign priority is claimed provided the foreign patent application sufficiently describes the claimed invention.
 
Even if the subject matter sought to be patented is not exactly shown by the prior art, and involves one or more differences over the most nearly similar thing already known, a patent may still be refused if the differences would be obvious. The subject matter sought to be patented must be sufficiently different from what has been used or described before that it may be said to be non-obvious to a person having ordinary skill in the area of technology related to the invention. For example, the substitution of one color for another, or changes in size, are ordinarily not patentable.