This document discusses using social media, specifically Twitter and Facebook, on mobile devices. It provides the following key points: 1. Twitter and Facebook have large mobile user bases, with 42% of Twitter's interface via mobile and over 100 million active Facebook users on mobile. 2. Facebook has over 400 million active users who generate over 3 billion photos and 5 billion pieces of shared content per week. 3. The document recommends companies have a mobile-optimized presence on Twitter and Facebook to engage with consumers across platforms and devices.