The document summarizes key factors that have contributed to Facebook's success: 1. Facebook predicted shifting user needs to focus on text conversations and relationships, and adapted its light platform to mobile connectivity. 2. Facebook solved problems with existing services, like security, by requiring real names and emails for registration and a reporting system for malicious comments. 3. Facebook's semantic search system prioritizes the opinions of friends, showing liked products at the top of search results. 4. Facebook developed smart business models including games like FarmVille and social shopping with Amazon, generating revenue through fees and Facebook Credit transactions.