How to check if a patent exists
You can search the patent number at the uspto.gov web site and Select Patents, and then Search for Patents. Once there, you can type in the patent number to see if the patent exists. If you want to know more than if a patent number, but want to see if a concept has been patented, then you need to do a patent search. First think of major terms or categories of your idea, then brainstorm terms to describe your idea based on its purpose, composition and use and find initial relevant Cooperative Patent Classification using the USPTO website's Site Search box (www.uspto.gov). Retrieve U.S. patent documents with the CPC classification you selected in the PatFT (Patents Full-Text and Image) database (http://patft.uspto.gov). Review and narrow down the most relevant patent publications by initially focusing on the front page information of abstract and representative drawings. After locating most relevant patent publications, review for similarity to your invention, paying close attention to the additional drawing pages, the specification and especially the claims. References cited in the patents may lead you to additional relevant patents. Broaden your search to find additional U.S. patent publications using keyword searching in PatFT or AppFT databases, classification searching of non-U.S. patents on the European Patent Office's Worldwide Espacenet patent database (http://worldwide.espacenet.com) and searching non-patent literature disclosures of inventions using the free electronic and print resources such as google search engine, among others. Start at http://patft.uspto.gov and now start searching by entering your query. Patent searches may also be done at our site, at www.inventiv.org, google.com/patents, and at a number of other free sites.