You just had a brilliant idea; one that will help people and maybe even change the world. But you would like to receive compensation for your invention, and you realize that the only way that will happen is if you apply for and receive a patent. Applying for a patent is a complicated process; in many cases, you will best be served by working with a patent attorney. However, if you are interested in the process, here is how you apply for a patent.
First, you need to describe your invention in detail. Generally, a patent application needs to describe the invention in such detail that a person of ordinary skill in the art (think a skilled craftsman or a journeyman in the trades) can implement every aspect of the invention. In almost every case, you will need to include one or more drawings, which the PTO requires to be in a particular format. See 37 CFR 1.84.
Second, after the invention is described in sufficient detail, you need to include a summary of the invention and abstract. The summary of the invention provides an abbreviated description of the invention, while the abstract does the same but must be 150 words or less.
Finally, the application requires a set of claims. Claims are similar to a property description in a deed, and set forth the metes and bounds of the protection sought by the inventor. Claim language is a highly technical subject, and numerous references have been drafted on the subject.
Once the application has been drafted, it must be filed with the United States Patent & Trademark Office. Along with the application you will need to include an Application Data Sheet and an Oath or Declaration. In certain circumstances, other forms can be required as well.
A well drafted patent application directed to a valuable innovation can have enormous value; in some cases, measured in the millions of dollars. In most cases, you will be served better by working with a Chicago area patent attorney. However, the above sets forth the basics of the process of drafting and applying for a patent.