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Unique Visitors: Where Everybody Knows Your Name (For a Little While)


It’s the simplest, most common metric associated with web analytics.  If it’s not the actual metric, it’s certainly part of the metric being analyzed.  We’re talking about visitors – specifically unique visitors.

Many enterprise-level testing tools like Adobe® Test&Target™ and Visual Website Optimizer default to unique visitors when reporting, so it’s a good opportunity for all of us to have a quick refresher course.

A unique visitor is someone who visits the site within a specific timeframe.  This timeframe can be defined as one week, one month, etc.  No matter how many times this visitor comes to the site during the defined timeframe (1 or 100+), they will be counted as one visitor.  If this visitor comes to the site from another computer, uses a different browser, deletes cookies or completes a conversion, they will be counted as a separate unique visit upon return.

Since there is a specific timeframe in place, the data is cleared upon expiration.  If a user came to the site during the first session and again during the next session, they would be counted as a unique visitor twice – once during each session.




In Test&Target, visits are identified by the pcID in an mbox cookie.  A pcID is an identifier for a visitor’s browser, and it lasts 14 days.

Unique visitors give you a picture of what overall experience converted.  A unique visitor may come to the site 10 times before converting, so the conversion data shows the complete conversion cycle per unique visitor.

This begs the question, don’t those 10 times mentioned above count for anything?  Yes, they count toward visits.

A visit refers to a visitor’s session on a site.  The visit ends when a user closes their browser, leaves the site or is inactive for 30 minutes.  If the visitor comes back to the site after a previous visit ended or comes to the site from a different computer, it will count as a new visit.  Additionally, the visitor may look at any number of pages, but it counts as one visit.




In Test&Target, visits are tracked by a sessionID in an mbox cookie.  A sessionID is a unique identifier for a session, and defaults to 30 minutes.

Unique visitors and visits are super simple and you already know this stuff, right?  Try out this pop quiz!

Assume that the user closes their browser after each visit, and that the unique visitor timeframe is 30 days.


What is the number of Unique Visitors?

What is the number of Visits?

Check out the answers below.

If the pop quiz made you stop and think for even a second, then my job is done!  It’s a good practice for conversion experts to take a moment to reflect on the basics and see if/how they’ve changed over time.  Unique visitors / visits are so important and are part of every metric that we analyze.  It’s important that we fully understand the way they work and constantly revisit these basic principles.


Brought to you by Suzi Tripp and Naoshi Yamauchi.


What is the number of Unique Visitors? 2

The initial visit was the first UV.  The visit after the user cleared their cookies was UV #2.

What is the number of Visits? 5

The initial visit was the first UV.  The next visit occurred just 10 minutes later, so it was not a new visit.  The visit prior to clearing cookies was #2.  The three visits following the cookies being cleared count as #3, #4 and #5.