Click fraud! What is it, by the way?

Some call it click frauds. To some, it's invalid clicks. Nonetheless, only a number dared to question why these clicks happen and how they happen. Are there any dirty secrets behind?
Some critics in the SEO industry linked click frauds to 30% percent of traffic for a given website. However, according to some search engines, this analysis is flawed.
"Our aim in fighting invalid clicks is broader and includes clicks that we suspect may have been deceptive or malicious, as well as clicks that we deem invalid for other reasons, such as accidental double clicking on an ad. The usage of the word "fraud" in this context has caused a great deal of confusion, as it's practically impossible to "prove" that an impression or click was caused by deliberate deception. Our servers can accurately count clicks on ads, but we cannot know what the intent of a clicking user was when they made that click. When we identify a click as invalid, it simply means a click we won't charge for, in order to deliver the best ROI to advertisers," Google explains.
Click fraud is a hit because it Lures significant number of visitors. The consequence of which is an overwhelming gain. Several websites gain hundreds of thousands of dollars just by indulging in click frauds. Click fraud suggests collusion or conspiracy to commit deception, not good a behavior though. However, it isn't illegal – not yet.