This document discusses social search engines, which take a user's social graph into account when returning search results. It provides three types of social searches: collective social search, which leverages trends from a network; friend-filtered social search, which shows what a user's friends have shared; and collaborative search, where users work together to find answers. The document also outlines benefits of social search like increased relevance and current results, and concludes that social search complements collaborative information seeking by allowing temporary collaboration during individual searches.