Social Information Access: Definition and Classification.- Privacy in Social Information Access.- Social Q&A.- Collaborative Information Search.- Social Navigation.- Tag-Based Navigation and Visualization.- Social Search.- Network-Based Social Search.- Accessing Information with Tags: Search and Ranking.- Rating-Based Collaborative Filtering: Algorithms and Evaluation.- Recommendations Based on Social Links.- Tag-Based Recommendation.- From Opinions to Recommendations.- Recommending Based on Implicit Feedback.- People Recommendation on Social Media.- Location Recommendation with Social Media Data.