Most people use Wikipedia. It's a staple of the internet and rightfully so - There is nowhere else you can go to find the depth and breadth of so many tv sh... Wait, I mean subjects.
Did you know that there is a lot more to Wiki than the 'pedia' part? Wikimedia Projects is full of amazing stuff as part of its mission for free knowledge for all. You can find books, courses, news, software, dictionaries, quotes, original translations, historical documents, instructional materials, a world-wide travel guide, a world of data and reusable media. There's also the Wiki that I get lost in - Wikispecies. Animals, plants and biology - Very cool.