Jason Butcher

Google Analytics (abbreviated GA) is a free service offered by Google that generates detailed statistics about the visitors to a website. Its main highlight is that the product is aimed at marketers as opposed to webmasters and technologists from which the industry of web analytics originally grew.
GA’s approach is to show high level dashboard-type data for the casual user, and more in-depth data further into the report set. Through the use of GA analysis, poor performing pages can be identified using techniques such as funnel visualization, where visitors came from (referrers), how long they stayed and their geographical position. It also provides more advanced features, including custom visitor segmentation.
GA can track visitors from all referrers, including search engines, display advertising, pay-per-click networks, email marketing and digital collateral such as links within PDF documents.
Integrated with AdWords, users can review online campaigns by tracking landing page quality and conversions (goals). Goals might include sales, lead generation, viewing a specific page, or downloading a particular file. These can also be monetized. By using GA, marketers can determine which ads are performing, and which are not, providing the information to optimise or cull campaigns.
Google Analytics is implemented by including what is known as a “page tag”. This is referred to as the Google Analytics Tracking Code (GATC) and is a hidden snippet of JavaScript code that the user adds onto every page of their website. This code acts as a beacon, collecting private visitor data and sending it back to Google data collection servers for processing. Data processing takes place hourly, though it can be 3-4 hours in arrears of real time.
To function, the GATC loads a larger file from the Google webserver and then sets variables with the user’s account number. The larger file (currently known as ga.js) is typically 18 KB in size and is only downloaded once at the start of the visit as it will be cached throughout the session. As all websites that implement GA with the ga.js code are using the same master file from Google, a visitor that has previously visited any other website with this code implemented, will also have the file cached on their machine. The result is that the page overhead of including the GATC on web pages is kept to a minimum.
In addition to broadcasting information to Google servers, the GATC sets first party cookies on each visitor’s computer. This is used to store anonymous information such as whether the visitor has been to the site before (new or returning visitor), what is the timestamp of the current visit and what was the referrer site or campaign the visitor came from e.g. search engine, keywords, banner, email etc.