Social intelligence involves the ability to successfully build relationships and navigate social environments. Strong relationships improve health while loneliness causes stress and health problems. Social intelligence was first defined by Edward Thorndike as understanding and managing people. It involves skills learned over time rather than being innate. The brain has structures like spindle cells and mirror neurons that help guide social decisions and predict others' behavior. Signs of social intelligence include effective listening, conversation skills, and lack of arguing. Developing it involves paying attention to others, increasing emotional intelligence, and practicing active listening.