Google Analytics is one more tool that offers a free search engine for its users. The procedure is simple. The user uploads a piece of code to your site, and from that time, Google may record the number of visitors the site has had over a period of time. The reality is that the tool is very good in the sense of its versatility and the ability to analyze information from different points of view: the country of origin of visitors, origin of traffic, keywords that generated the visit, etc … Also , Google offers several ways of presenting information: axial graphs, colored maps, etc … Much is said about Google metrics, in that often "demonized" everything from Google, like a big brother who attempts to control life. Google's goal would be something like the Internet itself as synonymous, and that everything that happens online, it goes through Google.
This is a matter of discussion, almost philosophical level. The reality is that one of the most common situations are given to compare the metrics of Google with those of our own server, or a private service we have contracted to monitor traffic to our site. Usually differences, and indeed, it would be rare to find a Google Analytics report reflecting the same numbers as the third. The question is why. The intention is not to assign blame or make value judgments. The idea is simply to get into the specific analysis of the facts to have a clearer idea of what our real traffic.