Wikipedia founder Jimmy Whales probably puts it best:
Wikipedia is based on a very radical idea, the realization of the dreams most of us have always had for what the Internet can and should become. Thousands of people, all over the world, from all cultures, working together in harmony to freely share clear, factual, unbiased information… a simple and pure desire to make the world a better place.
I use Wikipedia to research a lot of my posts and provide answers to many of the nagging questions I have about topics and love it to pieces. And for anyone who thinks it's an unreliable source, check out the recent research which shows it's about as accurate and the Encyclopedia Britannica.