This document discusses how social signals like Facebook likes and Google +1s can impact search engine rankings. It includes: 1. Two experiments showing that while Facebook likes no longer directly impact indexing, they can still indirectly influence rankings through increased traffic and links. 2. A separate experiment showing that adding "real" Google +1s to pages led to sustained ranking increases for most pages within a few days, indicating +1s are a ranking factor. 3. Tips for succeeding at personalized search like influencing a user's search history in your brand's favor, appearing for related queries, encouraging return visits through good content, and linking to search results from other marketing efforts.