Facebook is a very useful tool. That said, it is also one of the worst sites on the 'net for privacy issues. Make sure you regularly check your account privacy settings to ensure that they are where you'd like them to be. The default setting shares pretty much everything about you. Anytime you click the Facebook "Like" button on another website, it too, shares all of your information with that site. Know your risks and be vigilant.
It's a good site plus it's entertaining! Idk why u stupid peeps are saying it's not safe! it's kinda child friendly. It's not like the pictures of people are naked! anyways just because some ads are not safe?!!? Ads aren't even part of facebook!!! they're just advertisement! All u gotta do is NOT go on it! SIMPLE!