Let's talk about intellectual property for a while. Now, before we go any further, I must note that I am NOT a lawyer (I merely sleep with one) and CANNOT and WILL NOT offer any kind of legal advice. Everything I say here is liable to be incorrect. Do not rely on it. If something I discuss is relevant to you, do your own research and talk to a lawyer.
I'm also going to skate over the discussion of whether intellectual property is a valid concept.
So. There are four main types of intellectual property, and they all operate differently. We'll do them in alphabetical order, which means we start at C, for Copyright.
Copyright, at least as originally envisaged, is a way to make sure someone who writes a book, or a song, or something like that, gets paid for it. It provides an incentive to create by providing an exclusive right to profit from a creative work. It's supposed to expire after a time, but about once every 20 years or so, Disney demands that the term of it be extended by 20 years. Once copyright expires (or is explicitly disclaimed by the holder of the copyright) a work falls into the public domain, which means you can copy it and profit from it as you wish. There are some limited things which you can get away with when it comes to using bits of a work that's under copyright (such as, for example, using a short clip of Star Wars in your lecture about Where George Lucas Got His Ideas, as an illustration) but in general, it's a pretty strict law. The various music industry and movie industry lobbying groups keep on demanding ever more draconian punishments for violation of copyright, because they still haven't quite figured out that you can make a profit competing with "free" by making your option easier to use. But I digress. Now it's time for P, for Patents.
A patent is (or at least, is intended to be) a full description of A Method For Doing A Thing. Its value lies in the fact that in return for making it public (again, theoretically; more on that later) the person or entity who thought of that method and filed the patent gains exclusive rights to use said method. Your options here are supposed to be do it yourself, or sell licenses to other entities to allow them to use your method. Said licenses can be flat-fee or royalties. Whatever happens, its purpose is twofold: to allow you a reasonable period to profit from your invention while also making sure that once you've had a fair whack, EVERYONE can use said method because the details are public record. It used to be that patent examiners would examine the details of each patent, determining whether a thing being described really was a new idea (which is to say, not previously patented and not described in reference books; no sneakily patenting wheels!), whether it was properly described and suitably limited in scope, and whether or not it was something that could be considered "obvious". These days, they just let any old thing through (resulting, among other absurdities, in a plethora of patents for perpetual-motion machines) and let people sue each other to sort it out. This has led to the rise of the patent troll, whose method of working is to file or buy up a patent that's ridiculously broad (such as "use a computer to add up the total value of items a customer has ordered"), allow the method to become widely used by sitting on the patent (relying on the fact that NOBODY can possibly check EVERY patent granted, or even keep up with the stream of new grants), and then sue everybody. The hope is that the people they sue will choose to simply pay them a whack of cash rather than going through the hoopla of an actual trial. Most of the time, if it DOES go to trial, the troll gets told to nick off back under their bridge, and the offending patent gets invalidated. Now we get to T, for Trademarks.
Trademarks are a way of making the economy more stable, in the interests of making corporations a more viable entity. Pure corporate protectionism, and yet they're generally considered a good thing. Their purpose is consumer confidence; a trademark which is actively being used will NEVER expire unless the owners stop trying to maintain control, so you can always be sure that, for example, that beer with the red triangle on the container is Bass. What you think of the beer is another matter, but you know it's Bass. Car badges are also trademarked. Logotypes for companies. Trademarks are there to give you confidence that a thing displaying trademark X is made by or on behalf of the owners of trademark X. It's pure corporate protectionism with the force of law, but it's reasonable despite that. The expiry method is genericisation; a trademark can become so widely used as to become generic. The classic example, and a very bad example, is aspirin. Aspirin was originally a trademark for the acetylsalicylic acid manufactured by Bayer. However, after WWI, the trademark was forcibly made generic. A better example for the UK is the colloquial use of "Hoover" for any vacuum cleaner. The Hoover company is very annoyed by this, as while it does increase the awareness of their brand, it also makes it harder for them to stop people selling knock-offs. The US has had similar things happen with Kleenex tissues and Band-Aid sticking plasters.
And finally we remain in T for Trade Secrets. Trade secrets are less protected by law than other forms of intellectual property, but that very fact makes them powerful. They're things like the formula for Coca-Cola, the blend of herbs and spices used in Kentucky Fried Chicken, and so on. They're the Wild West; there's virtually no law to prevent competitors from finding them out and using that knowledge, which is why they're kept SECRET. The flipside to the lack of protection is the complete lack of any legal means to force them into the open short of carefully crafted libel. One could theoretically figure out a slur that would require to exact formula for Coca-Cola to disprove, and then publish said slur. Chances are it wouldn't work out like that, though. English has too many ambiguities to allow a ploy like that, in my opinion.
And there you have it. Intellectual property, in a nutshell. Now if you're going to rant about one of them, you can at least be ranting about the right one!