Homeland security will now collect social media data on all immigrants. This is a news memo that came out that the USCIS and Department of State can start reviewing social media like Facebook and they can start looking at all of your posts. Anything that you post on the web is not only there temporarily but it's there forever. So keep in mind that that is now accessible and will be used in the review process and will be considered when they look to approve your visa. So be prepared to speak to it if you have any information out there that could be questionable.
Anything you put online is never going to be temporary. You can delete it and it's still going to be available. Just be careful what you put online. No matter how much you could have your social media locked down, it would be naïve to think that that stuff is private or that only your close circle of friends are going to know about it. Be aware they're collecting that now and you should expect that they'll be looking at it.