This document provides 20 facts about social media. Some key points include: Edgerank is Facebook's algorithm that determines reach, similar to Google's PageRank. Multimedia content gains more reach than text posts. Posts on weekends and at 3pm on weekdays receive more interaction. Females aged 25-34 are most active on Facebook interacting with brands. Less than 30% of fans see a brand's posts and less than 20% of fans visit a page more than once. Facebook has guidelines for promotions and contests. Other platforms like YouTube, SlideShare and LinkedIn are also mentioned.