Google Analytics collects the date the moment that visitor navigates to one of the web pages in browser. Embedded within web page content, there is a small block of JavaScript code referred as GATC (Google Analytics Tracking Code)
When the visitor's browser loads the web page, it runs GATC which performs key analytics operations. First, it loads the Google Analytics master JavaScript file (ga.js) by downloading from Google servers. This code collects data about the visitor (like browser type, version, resolution, page title, etc.) from the browser. 5 cookies (ref image) determine whether the visitor is a repeat to the site with tracking information. Finally, it transmits to the data collection server, in turn persisted as log file at Google.
During the day, Google performs the first pass of these log files on an hourly basis and then runs another more thorough reprocessing pass at the end of the day. Data sources are from raw click data and aggregated summary data in Google's big table database. End user can view the accessed report from Google Analytics web site.



