The document discusses several popular social media platforms, including Facebook, WhatsApp, Instagram, and Twitter. It provides background on each platform such as founders, usage statistics, and key features. Facebook allows users to share content and has over 2 billion monthly users. WhatsApp is a cross-platform messaging service with over 1 billion users that allows sharing of text, images, and videos. Instagram launched in 2010 as a photo sharing app and was acquired by Facebook for $1 billion. Twitter is a news and social platform where users share short messages known as tweets.