At first glance, patent law may seem dry and boring -- until you understand the stakes. Consider the lawsuit that NTP, a patent holding company, brought against Research In Motion (RIM), the maker of BlackBerry mobile devices. Intellectual property lawyers for NTP claimed that RIM was producing BlackBerry devices using a particular technology patented by NTP. In March 2006, RIM settled and paid NTP $612.5 million [source: Kelley]. Perhaps emboldened by its legal success, NTP has gone on to sue Apple, Google, Microsoft, HTC, LG and Motorola.

Now consider the challenges NTP faced to win its lawsuit against RIM. An average patent case will cost between $3 million and $10 million, and take two to three years to litigate [source: Hsieh].

You might think that patent holders who invest the time and money to protect their inventions have the upper hand in court, but that's not the case. In fact, patent holders lose against accused patent infringers about 75 percent of the time [source: Janicke]. And losing the exclusive rights to a highly innovative device or gadget can mean big bucks. Some patented products can generate hundreds of millions of dollars in revenue over their lifetimes. Remember Ron Popeil of "set it and forget it" fame? He earned nearly $1 billion in revenue from his Showtime Rotisserie BBQ [source: Perman].

Clearly, there's a lot to win and lose when it comes to developing and selling a great idea, which is why companies remain vigilant to find cases of patent infringement and why they hire high-paid, high-powered attorneys to prosecute infringers. But what exactly does it mean to infringe on a patent? Can you do it by accident, or is it always a malicious attack to steal something that doesn't belong to you? And what can inventors do to make sure they won't be financially ruined in the event of an infringement?

Those are the questions we'll tackle in this article. Up first, we cover the basics of patent infringement, starting with a refresher course on patents themselves.