Google's terms of service, while ignored by the vast majority of users, contain a pretty shocking clause: Under 18's are not permitted to use any of Google's Web properties. That's right, kids--no search, YouTube, Gmail, news, or images.
Under 18s wishing to watch YouTube videos of skateboarding dogs, or perform research for a school project will have to go elsewhere--Ask.com or Microsoft's Live.com search, perhaps. The message from Mountain View seems clear: We don't want your (underage) business.