The hacking industry is a multi-billion dollar money maker. The opportunity for someone to steel your account and pretend to be you for gain is big.
Main things to keep you safe:
1) Make your password secure and complex.
2) Regularly review your privacy settings. This is especially important on Facebook as they change
settings frequently. Better information on this can be gotten at Facebook privacy
3) Make sure you keep your twitter account secure. For more information on this go to
Twitter privacy