The average number of days between visits for a given visitor since tracking with persistent cookies and Visitor History began; for example, those who visit on average every 7 days. For a given visitor, a lapse of 12 days between the first and second visit, and a lapse of 24 days between the second and third visit, equals a latency of 18 days. Note that a zero latency means the average time between visits is less than 24 hours. If visitors did not visit the site during the report time period, their latency is not included.