What is it?
Unique visitors refers to the numbers of visits to a website per computer, with each computer's unique IP address only being counted once during a specific analysis period. It is also referred to as a unit of traffic.
How does it work?
Every computer has a unique IP address and when you visit a website for the first time it is counted as a unique visit. If you go on to visit that website 100 times, on the same computer, your computer's IP address still only counts for one unique visit.
Why is it useful?
Publishers and administrators of websites rely on visit reports to help them understand their site's popularity and use. A report usually includes the total number of visits, the unique visitor count, and other statistics, like how often a visit lasted and what pages in a website were visited.
What do you need to keep in mind about your child and unique visitors?
This measurement is really only of interest to the owners and operators of the web site. An exception may be if you are selling something such as real estate or on an auction site, when it is useful to know how many times the page has been viewed (but remember that this will simply be page views, and not the number of unique visitors).