5. The system of claim 1 , wherein identifying the one or more likely queries comprises: identifying the one or more likely queries using user activity sessions for at least a threshold number of users, wherein a user activity session describes activity of a particular user over a particular time period.
5. The system of claim 1 , wherein identifying the one or more likely queries comprises: identifying the one or more likely queries using user activity sessions for at least a threshold number of users, wherein a user activity session describes activity of a particular user over a particular time period. 6. The system of claim 5 , wherein the instructions are further operable to cause the one or more computers to perform operations comprising: inserting a particular query of the likely queries into the ranking of query completions, wherein the particular query did not previously occur in the ranking of query completions.