Atheism vs Agnosticism - What's the Difference?

An atheist is anyone who doesn't happen to believe in any gods, no matter what their reasons or how they approach the question of whether any gods exist. An agnostic is anyone who doesn't claim to know that any gods exist or not, no matter what their reasons or how they approach the question of whether any gods exist. This is also a simple concept, but it may be as widely misunderstood as atheism is.