have arisen with this method since its arrival in the early 1990s. First, it only measures hits, which as we mentioned above do not show a true picture of visitors. This was addressed when page views and visits were added. Search engine or robots (the methods used by search engines to crawl the internet and index websites) and other challenges such as caches then made it more difficult for server-based analytic to detect humans.This means that you may not see cached visits and may see some spider visits.