With the invention of the wi-fi laptop a few years ago, it's become harder to accurately track unique visitors to your website/ RSS feed/ blogsite visitors. Anyone who commutes a lot with a laptop may end up appearing as 3 or 4 different visitors in your web server access logs, possibly even as being from different cities. This of course inflates your readership/ subscriber numbers, which eventually may be something that advertisers, if you have any, may make you account for. While there is a new technique for identifying a computer anywhere geographically based each computer's unique clock skew, there's still the issue of accounting for Internet users that may use more than one computer in the course of a day.

Browser cookies work if visitors are using one computer each day, but at different locations (i.e., at least with different IP addresses, if not also geographically). However, cookies are unreliable and may get deleted.

Getting visitors to sign in works for some web sites, but may potentially reduce your readership if you force it upon everyone. Limited sign-on may be a better choice. For example, SlashDot lets anyone view their website, but you have to login to post a comment. You can datamine your web access logs and match them with logins, but only if every reader logins (not to mention, actually bothers to sign up).

In limited situations, logins may work - say for membership-only type of content. Examples would be sites serving up online course material, e-books, etc. But where does that leave other websites? One sinister, almost Big-Brother-like possibility is to force all users to access the Internet with some sort of card (e.g., credit card) or RFID-chip-based device. Let's hope this never comes to pass.

In the meantime, all we can do is make the assumption that each IP address represents a unique visitor and correct for this inaccuracy later, as we collect information through a variety of techniques.

(c) Copyright 2005-present, Raj Kumar Dash, http://geoplotting.blogspot.com