When more than two people file patent applications for the same invention, there are two principles: one is the first-to-invent principle, and the other is the first-to-file principle. The first-to-invent principle means that if two or more people file patent applications for the same invention, the patent right should be awarded to the person who made the invention first, regardless of the time when they filed the patent application. However, because when adopting this principle, many practical difficulties are often encountered in determining who is the first inventor, therefore, currently only a few countries in the world, such as the United States, Canada and the Philippines, adopt this principle. The so-called first-to-file principle means that when two or more people file separate applications for the same invention, the patent right will be granted to the latest person regardless of the order in which they made the invention. Whoever applies first, China and most countries in the world adopt this principle.