What to be careful for.
Computers know all...
Everything you do on the computer will be there forever. If you go to a website to buy items that you want or need, and you use a credit card, the company asks for your credit card number. Once you give it to them, they have it forever and if they have an untrustworthy worker, they could steal your card number and use it to buy things. You would have to go through a lot of work and cancel your account with your credit card because the person using it could keep using it and make you pay.
Credit Card Theft
Someone is about to steal her credit card number.
Attempting to take someones information.
If someone does get your information, remember to cancel the account so they have to stop using it.
What to watch for.
What you do on Facebook can be dangerous because they take all your information, lets say the games you play; they ask if they have permission to access your information and most people select 'accept'. That gives Facebook permission to see your stuff . There can also be weird creepers out there who lie about their age and information just to get to know you more. So, only add people who you actually know in person, as your friend.