Like most people, my knee-jerk response to tracking cookies is that they are evil and must be banished from my computer.
Then again, blocking cookies doesn't necessarily prevent sites from tracking you. The Electronic Frontier Foundation's Micah Lee explained in a June blog post on Deeplinks that when you open a Web page, your browser retrieves elements from many third-party servers.
Why 'Do Not Track' does not work
Enabling your browser's Do Not Track feature may not prevent your Web activities from being tracked, either. Adherence to the standard is voluntary, and many online advertisers are ignoring users' express wish not to be tracked, as Ed Bott describes in a post from September 2012.
The do-not-track movement got a boost last summer from the Digital Advertising Alliance's unveiling of the AdChoice icon that appears alongside some Web ads. As Dara Kerr reported in July, the program is intended to provide users with information about the data the ads collect, as well as giving them a do-not-track option.
The Digital Advertising Alliance offers its own page for opting out of tracking cookies placed by its member advertisers. However, you're opting out of only "interest-based" ads from the companies and will continue to be served up other ads.
In a post in 2011 I described how to block third-party cookies in Internet Explorer, Firefox, and Google Chrome. Earlier this year when the Mozilla Foundation decided to block third-party cookies by default in Firefox, the Interactive Advertising Bureau countered with an FAQ explaining why the decision hurts consumers and small businesses.
Another antitracking alternative is to use the free Adblock Plus browser extension that's available for Firefox, Google Chrome, Internet Explorer, Android, and Opera. In June's "Selective ad blocking lets you support your favorite sites" I explained how to use the add-on to block some or all ads.
Get a graphical view of your browser's trackers
If cookie-blocking and do-not-track options don't prevent your Web activities from being recorded and shared, maybe it's better to keep tabs on the trackers in real time. Mozilla's free Lightbeam add-on for Firefox is designed to show you via a 3D visualization the relationships between first- and third-party tracking cookies.
After you download and install the extension, the Lightbeam icon appears in the bottom-right corner of the browser window. Click it to open Lightbeam's default daily view, which is shown at the top of this post.
You can also view the cookies deposited by the most recent site you visited, by the last 10 sites you opened, and by all the sites you've browsed to over the past week. Hover over one of the icons in the graph to view the name of the company associated with the cookie.
When you click an icon in the graph you open a side panel listing your first and last access, the location of the company's server, and the total number of sites you've connected to since your first access.
Lightbeam's view options include visited sites, third-party sites, watched sites, blocked sites, connections, and cookies. You can change the visualization from graph to clock or list view.
Other Lightbeam options let you save or reset the tracking data the program has collected. You can add your cookie collection to Lightbeam's database by toggling the Contribute Data control in the top-right corner of the screen to On and accepting the privacy notice that explains how the data you upload will be used.
Online trackers are poised to move beyond cookies
Whether the demise of third-party cookies will allow a handful of Internet behemoths to dominate the industry and force out small and midsize organizations is an open question. It's telling that Google and Microsoft are working separately on tracking technologies that don't rely on cookies.
As CNET's Seth Rosenblatt reported in September, Google's AdID program is intended to give consumers "more privacy and control over how they browse the Web," according to an anonymous source quoted by USA Today.
Microsoft's plans to move beyond cookies for tracking users are described in a post from last month by Lance Whitney. The post cites an Ad Age article stating that Microsoft's cookieless tracking technology would encompass not only browser tracking but also the monitoring of people using Windows-based mobile devices and Xbox consoles.