Patentability
One of the most basic, fundamental laws regarding patentability is that the subject matter must be created by man.

Human organisms of any kind (whether embryos or fetuses) are never patentable.  Natural phenomena are also never patentable, so it isn’t possible to patent the laws of physics, natural plants or minerals, and many other non-man-made objects. However, an individual may find a new use for a natural object.  For example, a chemical may be extracted from a plant and used to develop a new drug. Inventions such as these may qualify for a patent.

There are three basic criteria for a patentable invention. In order for the PTO to consider an invention patentable, it must be novel, nonobvious and possess a utility. Inventions without these qualities are always found unpatentable. Let's break the three criteria down and summarize them.

Novelty. The invention must be new and different from items that already exist. The PTO won't let different people patent the same invention, only new inventions qualify. It's that simple.

Nonobvious. The invention can't be obvious. You cannot take an old invention and modify it in an obvious way. Combining two older inventions together also does not result in a patentable invention, unless their combination results in new and unexpected results.

Utility. The invention must be useful. It doesn't matter if it only works some of the time, as long as it provides a useful benefit, it may meet the utility requirement.

Inventive Types
In addition to the patentability criteria of an invention, there are different types of invention. Generally speaking, inventions may qualify for one of three patent types; a utility, a design or a plant patent.

Examples of utility based inventions are virtually everywhere. A rocket engine, paperclip and a new drug are all examples of utility based inventions. The variety between these objects is vast, but they all fit under the same category.

Design patents are those that incorporate a design into an object of manufacture. A good example is a new design for a headboard.

Lastly, plant patents are those that cover new plant varieties. Those that have been bred are acceptable, while plants growing naturally do not qualify.