Unique visitor
Definition
A unique visitor is a person who visits a website or online platform, but is only counted once, even if they visit multiple times in a given period of time. Unique visitors are typically counted using a combination of techniques, including cookies, IP addresses, and device fingerprints, to ensure that each visitor is only counted once.[1]
Unique visitors as a metric
Unique visitors are an important metric for website owners and marketers, as they provide a measure of the total number of people who are visiting a site. This can be useful for understanding the reach and popularity of a website, as well as for identifying trends and patterns in website traffic.
It's important to note that unique visitors are different from pageviews, which count each individual pageview separately, regardless of whether it comes from the same visitor or not. A single unique visitor may generate multiple pageviews if they visit multiple pages on a website.
Counting unique visitors
There are several methods that can be used to determine the unique visitors of a website. Some common methods include:
Cookies
Websites can use cookies, which are small pieces of data stored on a user's device, to track the number of unique visitors to the site. This is done by setting a unique cookie on a user's device the first time they visit the site, and then checking for the presence of that cookie on subsequent visits. If the cookie is present, it means that the visitor has been counted before, and they are not counted as a new unique visitor.
IP addresses
The IP address of a device can be used to identify unique visitors to a website. This is done by storing the IP address of each visitor in a database, and then checking for the presence of that IP address on subsequent visits. If the IP address is present, it means that the visitor has been counted before, and they are not counted as a new unique visitor.
Device fingerprints
A device fingerprint is a unique identifier that is generated based on the characteristics of a device, such as its operating system, browser version, and screen resolution. Device fingerprints can be used to track the number of unique visitors to a website by storing the fingerprint of each visitor in a database and checking for the presence of that fingerprint on subsequent visits.
Inaccuracies in tracking
There are a few potential sources of inaccuracies or measurement errors when it comes to tracking unique visitors on a website. Here are a few examples:
Some web analytics tools use cookies to track unique visitors. However, if a user clears their cookies, or accesses the website from a different device or browser that does not have the cookie, they may be counted as a new unique visitor.
Some tools may use a user's IP address to track unique visitors. However, if a user is behind a proxy server or is using a virtual private network (VPN), their IP address may be masked, and they may be counted as a new unique visitor.
It is possible for bot traffic to be counted as unique visitors. This can happen if the bot is able to bypass the measures put in place to detect and exclude it from the traffic data.
If a website is using multiple web analytics tools, or if there are discrepancies in the tracking code across different pages of the website, it can result in inconsistent tracking of unique visitors.
Finally, there is always the possibility of human error in the data collection and analysis process, which can lead to inaccuracies in the tracking of unique visitors.
Related links
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