What is Bitcoin?
Bitcoin is a peer-to-peer payment system and digital currency introduced as open source software in 2009. It is a cryptocurrency, so-called because it uses cryptography to control the creation and transfer of money. Conventionally, the capitalized word "Bitcoin" refers to the technology and network, whereas lowercase "bitcoin" refers to the currency itself.
From Wikipedia. We couldn't have said it better :)
How does Bitcoin work?
If you want to understand how Bitcoin works, this video should anwser a lot of questions.
For a written explanation (with graphics) see the bitcoin.org page on the subject.
Where do I get some bitcoins?
There are many many ways! Circle is a good place to start.
The easiest way we found was CoinBase.com, but the company asks for and stores your personal information. If you send your payments using your coinbase account, your email address might be reveled to the receiver as well.
Spanish users: Visita DiarioBitcoin.com donde podrás encontrar mucha información al respecto.