The answer is money. This page provides information on the types of patents and types of patent applications, and the examination process.Preparing a patent application and engaging in the USPTO proceedings to obtain the patent requires knowledge of patent law and USPTO procedures. Guide to searching among United States and foreign patents (prior art) to determine whether an idea can be patented. This question is based upon a false premise. The distinction between a WIPO patent and a U.S. patent is a category error. This tutorial will focus on patents and the process for securing a patent in the U.S. First, let's consider why we have a patent system? PCT is used to file a U.S. patent application under the Paris Convention to reserve patent rights in many other countries. Patents filed through PCT route have a WO kind code in the prefix of the publication number. A detailed list of kind codes may be found here.