Patent numbers provide the details of a patented utility, design or plant. This number is an eight-character identifier, states the United States Patent and Trademark Office. Each patent number is unique and can be traced back to the owner of the patent.
Usually, utility patents consist of six to seven digits. If a patent is reissued, it starts with "Re" followed by a six-digit number. Plant patents usually begin with "PP" followed by a six-digit number, and design patents begin with a "D" followed by a seven-digit number. Similarly, there are different alphabets to signify the category of the patent followed by an assigned number of digits, says the USPTO.