Different kinds of patents exist in order to cover the different types of inventions one might want to maintain exclusive rights over. The three different kinds of patents are: utility patents, design patents and plant patents.
Utility patents are the primary vehicle used by the United States Patent and Trademark Office to protect useful and new inventive concepts. Utility patents are monopoly rights that last for 20 years from the date of filing of the patent application. They are examined by the Patent Office for novelty and obviousness. The utility patents are a grant of a monopoly right for that limited duration of time. As its name suggests, the utility patent requires a full disclosure to the United States Patent and Trademark Office of how one with skill in the art can make and use your invention and it requires the filing of a patent application.
There are two kinds of patent applications, one is the provisional and one is the utility patent application, both of which result in a utility patent since the provisional application is essentially just a provisional utility patent application. After one year, you file a utility patent application and after the four years, the utility is granted.
Four years, why? This is just because the Patent Office needs that time to review the case, object and reject anything based on prior art and potentially issue a granted patent on the breadth and narrowness of the claims that are written. The utility patent is the foundational kind of patent because it protects the useful and inventive objects themselves.
The second kind of patent is a design patent. A design patent protects the ornamental or aesthetic features of an object – that is, how an object looks. Consider for example, this bottle of water. The ridges and curves are the exterior features of this bottle that we can see and feel and are therefore considered ornamental. If we wanted to prevent others from taking those ornamental design elements and using them on their water bottles, we could protect our bottle with a design patent. While copyright law provides another vehicle to do that, design patents usually deal with physical articles and physical goods and protect the ornamental features of those physical articles and physical goods.
The third kind of patent is known as a plant patent. As its name suggests, the plant patent is a very specific kind of patent that protects new plant and flower varieties for those that are reproduced asexually (by means other than seeding such as grafting or using rooting cuttings). The Plant Variety Protection Act protects plants that reproduce sexually via pollination (seeds), and presently both types may be protected by utility patents. So if you are in the business of genetically engineering a new kind of plant or variety of a plant, your plant could be protected with this third type of patent. Plant patents have a shorter term and the requirements for this type of patent vary significantly from the other two kinds of patents. It is important to note that questions regarding this type of patent should be directed to the Patent and Trademark Office and not the Department of Agriculture.
These are the three broad types of patents. The utility patents, which require an application that goes for four years, can be provisional utility applications. Although it may sometimes be difficult to distinguish between the first two types, it may help to remember that utility patents protect the useful aspects of new inventions, while design patents protect the ornamental features of those useful objects. Plant patents simply cover asexually reproducible varieties.