Anyone who has needed to copyright something has likely considered the option of the so-called “poor man’s copyright.” This is where you mail yourself a copy of the work to get a postal date on the envelope proving when you mailed the material. You keep the envelope sealed and, if there is ever a dispute about when you created the content, you can present the sealed envelope with the material inside as proof.

There is no provision in U.S. copyright law that approves this type of protection. It doesn’t work. And yet the strategy has been so widely circulated over the decades that it has also been proposed as a means to patent something on your own.

That won’t work, either.

Here are three other common myths about patents you should know:

Myth: Ideas can be patented. Inventions start with an idea, but the idea itself cannot be patented. It’s a blurry line between idea and invention. You do not need a prototype before you seek a patent, but an idea itself is too abstract. The U.S. Patent and Trademark Office (USPTO) also makes it clear that natural phenomena, artistic works and offensive or non-useful ideas cannot be patented. It’s wise to work with a knowledgeable patent lawyer who can help determine when applying for a patent makes sense.

Myth: Patent rights are worldwide. It is not possible to obtain an international patent. The rights granted by a U.S. patent only protect your invention in the U.S. Because most countries have their own patent laws, it is necessary to apply for a patent in each country you seek protection. The World Intellectual Property Organization (WIPO) maintains a list of contact information for IP offices worldwide.

Myth: A patent owner has the right to make and sell an invention. The patent grant is a “negative right,” meaning the patentee has the right to exclude others from making, using, selling or importing the invention. In fact, one patent holder may be able to exclude another patent holder from making or using an invention if aspects of the second patent holder’s patent fall under the first patent holder’s patent.

If that all sounds complex, it’s because it is. Patents and copyrights do very different things and can be difficult to understand. Inventors, artists, writers and other creative types should do what they do best and trust the legal aspects of protecting what they produce to experienced IP attorneys.