A business owner wants to understand his customers to create a better product. A marketer wants to understand her customers to create a better campaign strategy. An operations manager wants to understand his customers to provide the best service. It doesn’t matter which profile we work in, understanding our customers is at the heart of everything– and this is why “Visitor Tracking” is one central concept of any web analytics tool/service.

We briefly discussed visitor tracking in data collection process of Google Analytics, now let’s discuss it in a greater detail. First, We will go through a common misconception that visitors are tracked using IP addresses. Then, we will see how cookies are a much better option for visitor tracking along with some of its limitations.

Are visitors tracked using IP addresses? (Misconception)

Internet connection through ISP
1.) Internet connection through ISP

First thing first, IP addresses cannot be used for visitor tracking. When a visitor tries to access the web, he is given a Public IP Address by the Internet Service Provider’s (ISP) system because Public IP Address is required to access the web.

Visitors are not tracked using their IP Address

If you consider the explosive growth in the number of people accessing internet around the world, you will quickly realize that these IP Addresses are only limited in number. To tackle this issue, computers no longer rely on unique Public IP Addresses of their own, instead they are allotted these on the fly by their ISPs when they connect to the internet. This means that a person’s Public IP Address depends on its availability, and it can change overtime.

PRO TIP : You can check that Public IP Address changes when you turn off your router and then turn it back on.

Not just that, hundreds of people could be connected through one Public IP Address at a time. So, it is imperative that we ignore it for visitor tracking because it will consider all people connected through same IP Address as ONE (1).

HEADS UP ! IP Addresses might not be good for Visitor Tracking, but they are used to find the estimated location of visitors.

How are visitors really tracked?

Visitors are tracked using “Cookies,” now let’s see how. In our post regarding data collection of Google Analytics, we learnt that once a tracking code is added to all pages on site, on every page load, a hit is sent over to GA servers.

Request Response
2.) Request – Response

Now, in computer networking, if any system (A) sends information, also called request, to another system (B), then B has to send a response back to A to signal success or failure of the request. Think of it like a receipt of a credit card transaction. So far, the information has flown from browser to GA server. Now the response has to be sent back.

Visitors are tracked through a unique ID called “Client ID” saved in “Cookies.”

Analytics tools handle these responses rather cheekily. Google Analytics sends in a two-step-response to ensure that it handles visitor tracking within this step also.

In a two-step-response, google first checks if the visitor already has a visitor identification cookie on his/her computer. If this visitor is new or he just deleted his cookies, these would not be present, and this is where GA will create new cookies.

Cookies remain as the most reliable way to track visitors, and it contains a unique ID (Google calls it “Client ID”) to identify users. Once a Client ID is used for a visitor, the same ID will never be given to any other person in the world! In fact, if a person deletes his own cookies, the same Client ID will not even be given to him, so essentially, he will be treated as a new visitor afterwards.

HEADS UP ! Google does this on every hit, so even if a user deletes his cookies in the middle of a session, a new cookie will be created for him on his next hit.

Once data is collected and Google has made sure that the visitor is being tracked, it proceeds to the second and last step of the response. This response will be either success or failure itself. This is the final confirmation from GA’s server.

Limitations of using cookies for Visitor Tracking

3.) Bad Cookie

Using cookies is a great option to track various things over the web. However, everything comes with its own set of limitations. Here are some limitations of this method you need to know:

  1. Cookies can be deleted.
    This one is a no-brainer. Visitor can delete cookies through browser settings. Once GA cookies are deleted, even the same user will never get the same “Client ID” again. Therefore, he will be considered as a new visitor. This may inflate visitors.
  2. Cookies are browser-specific.
    Due to privacy policy of all operating systems, one installed program can only access its own files. This makes sure that programs installed cannot access your private pictures, documents, etc.
    However, this also means that one browser cannot access another browser’s cookies. So, if a user accesses your website through Chrome as well as Firefox, the same user will be considered as 2 different users.
  3. Incognito Mode.
    Incognito Mode is available for most browsers, and it is used widely. Don’t know what it is? Click here to find out. Incognito Mode and Normal Browser work just like two different browsers. So, if one user is using both of these browsers, he/she will be counted twice.
    Moreover, there is one more interesting aspect of Incognito Mode. When a user closes all the tabs/instances of Incognito Mode, it automatically deletes all cookies stored. Hence, the same user may be considered as a new user everyday if this user accesses your website through incognito mode only and he closes all tabs everyday as well.

“Cookies” have a few limitations that may cause over-reporting in numbers

Conclusion & Summary

Visitor Tracking is a fundamental topic in Google Analytics that covers user identification through a unique ID using cookies. When a visitor arrives on your website, Google Analytics saves cookies on his/her device. This method provides a reliable way to track visitors. However, there are some limitations regarding them as well that you should always keep in mind. I hope that with this article, I was able to shed some light on that.

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