Unique Visitors represents the number of unduplicated (counted only once) visitors to your website over the course of a specified time period. A Unique Visitor is determined using cookies.

website themes might not play the main role of unique visitors unless your theme is poor enough to get your traffic leave your page once enter. It usually more related to where you get your traffic. Most target and related traffic allow you to get high unique traffic . That is why people do generate traffic from related site , target keywords, related market.