This lecture covers the early history of social media platforms like LinkedIn, YouTube, Facebook, Tumblr, Twitter, Pinterest, and Instagram. It explores the societal, economic, business, political, and technical perspectives of social media, emphasizing its role as a massive source of data for machine learning and AI techniques. The lecture delves into the use of social media in humanitarian sectors for identifying needs, helping people in distress, monitoring reputation, and providing early warning signals. It also discusses challenges in social media analysis, such as spotting relevant data, separating data from noise, and identifying influencers and relevant sources.