Each social media site has its own specific policies about who owns the information and what can be done with it. For example, according to Facebook's terms and conditions, you own all of the content and information you post on Facebook. By using Facebook, you are giving them a license, or right, to use any information you post subject to your privacy and application settings. These settings control how visible your content and information is on Facebook and search engines and how it is shared. Unless you change it, the default is that some of your profile information, like your name and photo can, also be searched on Google.
In addition, Facebook is about communities, and what is yours is theirs, too. That means your information and photos can end up in many places on Facebook, depending on how you use it. They do not give your information to advertisers however.
Facebook's terms of service (TOS) says that when you close your account on their network, any rights they claimed to the original content you uploaded, expire. There is an exception, based on the extent to which your content has been shared with others, and they have not deleted it. For example, if there's a picture of you with a group of friends and any of those friends tagged the photo on their active Facebook accounts, the picture with you in it, is still active on their account and is under Facebook's TOS.