http://twd6bfktlkhwluhj2ghjthx55pnp2dcuuhf6qqjz7vm2krsmwpz6crad.onion/investigating-social-media-accounts-and-profiles/index.html
For example, you can find general information such as name, city and state, and where someone works. Also, they can learn about their family, friends, co-workers, and personal interests.