Systems and methods that synchronize indexes are described. In one
embodiment, a first index on a first client can be provided, wherein the
first index comprises a plurality of terms associated with a plurality of
events, the events comprising client activity associated with an article,
and the first index can be synchronized with a second index or a second
client by sending events from the first client to the second client,
wherein the first and second indexes index the same events. In another
embodiment, an event is retrieved from a first client, wherein the event
comprises event data, the event is sent to a second client, the event is
received by the second client as a new event, the new event comprising
event data, a new event ID is associated with the new event, the new
event ID is indexed, and the new event is stored.