A patent only confers the right to exclude others from practicing a claimed (patented) technology. U.S.C. §271: "whoever without authority makes, uses, offers to sell, or sells any patented invention... infringes the patent." A patent grants no other authority.

What does that mean, practically? A patent is a license to stop others from using a technology; a governmental grant that can be sold, traded, or its usage licensed. Licensing amounts to forsaking enforcement of infringement.

A patent is an odd thing: an intangible asset - a commodity where the owner can grant an unlimited number of permits without diminishing the asset.

In other words, a patent is an abstract property - as many people/licensees can use the property as the owner tolerates.  It's like owning a bountiful, unbounded lake, where any number of people can fish, but only legally with a permit. Is it evil if the lake owner doesn't fish?

Is it evil if a patent owner doesn't practice the technology of the patent she holds? After all, a patent doesn't give the right to practice a technology, only to exclude others from practicing it, if the owner so chooses. Just as the lake owner does not guarantee the fishing experience, only the permission to fish.

Even if you have a patent, but may not be able to legally practice the technology, because someone else might have a patent that prevents it. In other words, there can be multiple patents on any product that could be made in a particular technology. This is true of numerous consumer electronics products, including, for example, cell phones. Hence, it only makes sense that a patent is nothing more than a governmental permit to exclude, granted sliver by sliver of innovation.

Thomas Edison, this country's most prolific inventor, with 1093 U.S. patents, never made products, and he fought to enforce his patent rights.

There has been much baying about "patent trolls" - patent owners that don't practice the technology for the patents they own. Once you understand the pith of patents, you realize how utterly ridiculous it is to complain about patent owners doing what they want with their limited right to exclude.

What is the fuss about? How did it get started?

"Patent troll" was coined by Peter Detkin* while corporate patent counsel at Intel, who was frustrated at not being given free rein to trample others' intellectual property rights. Crybaby Intel. Other corporate crybabies, like Microsoft and Oracle, joined in, sniveling self-serving tripe about how the patent system should work to their advantage.

As every good propagandist knows, repeat a lie often enough, and people will start to think it's the truth. And that's how it came to be: patent trolls = evil.

* By his own definition a hypocrite, Peter Detkin is now himself a patent troll.