In its simplest form, a cognitive bias is "wishful whinking" or a "mental shortcut". It is when we make a decision or judgment, which deviates from norm or rationality.
For me personally I view them as traps which should be avoided, to make sure that I arrive at the rational or best conclusion.
In marketing however, a company can see them as tools to make sure customers buy a more profitable product. I am probably stretching the term here, but this is what behavioral economics is about: Making money. Which umbrella term we decide to cover everything under is besides the point.
The creative use of cognitive biases to achieve your own personal goals could be seen as both good and bad. Some would argue that it is manipulation, others would call it social skills.
I'll leave it up to you to make a decision, keeping in mind that you might be under the influence of one or more cognitive biases when doing so.
Why rewrite everything when it is already available on Wikipedia? To better understand it myself and actually learn them. Some might call it "studying".
I find that I learn the best when I not only read about a topic, but treat the topic somehow. In case of cognitive biases, I am going to try and learn them the same way I studied in university. It must have done something right for me, I think.