From a different DHS document...

https://www.dhs.gov/publication/privacy-policy-operational-u...

"Social Media means the sphere of websites, applications, and web-based tools that connect users to engage in dialogue, share information and media, collaborate, and interact. Social media take many different forms, including but not limited to web-based communities and hosted services, social networking sites, video and photo sharing sites, blogs, virtual worlds, social bookmarking, and other emerging technologies."