This document discusses key metrics and strategies for social media marketing. It notes that 500 million tweets are sent per day and over 900 million people actively use Facebook daily. The psychology of sharing information online is explored, finding that people more deeply process information when they share it and reading other perspectives helps understanding. Different types of social media users are identified. Effective social media involves defining a brand voice and tone tailored to audience and channel. Metrics like engagement, traffic sources and qualitative vs quantitative data are important to measure performance. Tools can increase efficiency and case studies demonstrate best practices.