A specific IP address visiting a website for the first time in a certain period – usually a month or longer.

Most commonly used as useful data to advertisers and publishers, it gauges what size audience a website is acquiring. Within other modes of media, this may be referred to a “Reach”.

Unique Visitor traffic is calculated by requesting the users to log-in to a site thus preserving the users identity or placing a cookie on the users computer, corresponding this to an applicable database and recording subsequent appearances by that particular cookie.

See also:
Unique Page views
Reach
Cost per acquisition (CPA)
Cost per click (CPC)
Reciprocal links
Ad rotation
Ad impression
Behavioural Targeting
Contextual Marketing
RSS
E-Marketing
User Session
Deep Linking