Unique Visitors

In version 14, a unique visitor refers to a visitor who visits a site for the first time within a specified time period. For example, the unique visitor can visit a site ten times in a week, but if the time period is week, a single unique visitor is counted only once for that week. After that week is ended, that unique visitor can be counted again for a different time period.

Differences between version 14 and 15

version 14 does not remove duplicate Visits and Unique Visitors metrics from classifications-based reports. For example, if two video clips shared the same classification, a single visitor that viewed both clips generated two Visits and Unique Visitors in the classification-based report.

Version 15 removes duplicate Visits and Unique Visitors from the classification-based report. This is a more accurate measure of Visits and Visitors, but typically results in a decrease in your Visits and Unique Visitors metrics for classification-based reports, when compared to data collected prior to upgrade.

Uses Description
Traffic A visitor is a person that comes to your website. Does not require a persistent cookie.
Conversion A visitor is a person that comes to your website. Is counted when a conversion-related event or action occurs.
Ad Hoc Analysis A visitor is a person that comes to your website. Does not require a persistent cookie.

See Unique Visitors Report - Analytics.