It’s no secret: Every move you make on the Web is being tracked, recorded, compiled, and used to sell advertising or otherwise finance the sites that we all know and love. But such activity has come under increasing scrutiny from privacy advocates, and even the U.S. government. Which got me thinking: What are these companies that are doing the tracking? And which websites are they using to gather this information? Using two of the most popular anti-tracking extensions, Ghostery and Do Not Track Plus, I visited each of the top 100 most-visited websites in the U.S., according to Alexa, to dig a bit deeper into this whole tracking debacle.

In total, about 125 different companies or company products are used to track your online activity through the top 100 sites. Many of these are simple advertising networks — but others are particularly nefarious. To get a better sense of what each of these companies are, I reached out to attorney Sarah Downey, a privacy strategist for Abine, which created Do Not Track Plus. Based on her extensive research, here are some of the companies you should be most concerned about.

DoubleClick: One of the most prevalent trackers on the Web, DoubleClick was purchased by Google in 2008. The company specializes in ad delivery, analytics, and building user profiles. The problem with DoubleClick is its near-ubiquity, though there are some positive aspects. “Google says that they won’t collect user data that could be used to make guesses about sensitive categories, like political affiliations or medical conditions,” says Downey.

To opt-out of DoubleClick, click here.

Disqus: This has become one of the most popular third-party comment plugins on the Web. That’s because it provides some robust tools for website owners to help keep conversations civil, as all comments posted through Disqus by a single user are linked, dissuading trolliness. However, the service does carry its share of privacy concerns.

“People understand that the Disqus widget is a commenting system, but it’s also a tracking system. It follows a user’s activities across sites that use Disqus, even if the user is logged out,” says Downey. The info collected by Disqus includes IP address, browser version and installed plugins, and exit links — data Disqus refers to as “Non-Personally Identifiable Information.” However, this information can be used to de-anonymize users, when combined with third-party information. And because Disqus reserves the right to share you data with third-parties, such action could be taken. Furthermore, says Downey, “Disqus has come under fire for privacy issues after it published its users’ full commenting histories on user profile pages that were visible to the public.”

Disqus is opt-in only — if you use it, you are opting in.

Facebook Connect: Facebook Connect is a tool that allows third-party websites to let users log in using their Facebook credentials. The primary benefit is that it’s easy — you don’t have to create an entirely separate login to comment on the site. Problem is, logging in with Facebook Connect allows for far more sharing between the site and Facebook, explains Downey. This includes your “basic info” — age, gender, current location, hometown, email address, interests, and all pages you’ve “liked.”

But that’s just the beginning — relationships, the male/female make-up and size of your friends list, your education history, your friends’ education history, your work history, comment and wall post frequency, and how you interact with your friends can also be tracked and shared.

Facebook Connect is pseudo-opt-in-only, meaning that it can still gather information on you if one of your Facebook friends uses it, even if you do not.

Facebook Social Plugins: The “Like” buttons and other sharing buttons from Facebook allow the social network to track your Web browsing history without installing a cookie on your machine, says Downey. This gives Facebook the ability to “build a record of every time you load a page with embedded Facebook content,” according to the Electronic Frontier Foundation.

Opting-out is the same as Facebook Connect.

Omniture: Owned by Adobe and AKA Adobe Digital Marketing, Omniture is “one of the biggest players in the online ad industry,” says Downey. Omniture has been criticized for trying to hide its data collection processes. “They send data to a domain name that’s designed to look like a safe IP address: 192.168.112.2O7.net. Actually, the 0 in 207 is a letter O, as in Omniture,” explains Downey. “Critics said that Omniture and Adobe were intentionally trying to thwart firewall rules and inquisitive users.” Like DoubleClick and Facebook Connect, Omniture’s most troublesome aspect is its prevalence on the Web.

To opt-out of Omniture, click here and read the instructions.

KISSMetrics: An analytics and user profiling company, KISSMetrics allows customers to “go back and look at each person’s interaction history no matter where it happens, Web, mobile, social, desktop, and even offline,” according to the company’s website. As if that weren’t bad enough, the company came under fire earlier this year for using non-deleteable ETags to track users’ Web activity. The tracking tool was used on some major sites, including Spotify and Hulu, both of which have since stopped using KISSMetrics. In response, KISSMetrics itself overhauled its privacy policy, and stopped using ETags.

To opt-out of KISSMetrics, click here. (But be warned, the company does this by putting another cookie on your browser, and if you clear cookies, you automatically opt-in again.)

RapLeaf: RapLeaf is a “big data miner making extremely detailed consumer profiles,” says Downey. The company has also been in trouble in the past for selling information about Web users’ reading habits and other personal data to the Main GOP for election targeting, Downey explains, and for selling Facebook IDs to advertisers.

To opt-out of RapLeaf tracking, click here.

TargusInfo: Like RapLeaf, TargusInfo is a profiling and data enhancement company. It offers a service called CustomerComplete, which verifies people’s names, address, and phone numbers, and links those with secondary phone numbers, additional addresses, and email addresses. “It also scores customers on how valuable they are” to other companies, says Downey.

To opt out of TargusInfo data collection, click here.

Tynt Insight: Simlar to the previous two, Tynt Insight scans real-time user behaviors, including the tracking of copy and paste, which means “they actually see what parts of a page you are copying and pasting,” says Downey.

To opt-out of Tynt Insight, click here.

Baynote Observer: An ad delivery and user profiling company, Baynote Observer builds users profiles by tracking what you search for, which articles you read, what you share on social networks, geolocation, online purchases, links clicked, and videos watch. Baynote also supplements its profiles with third-party data and “like-minded user evaluations,” says Downey. The company specializes in on-site user tracking and ad targeting.

Baynote Observer does not offer way to opt-out.

AddThis: “Known for share and follow buttons, which are actually tracking users, AddThis tracks clicks, shares, viral lift, copied text and more,” explains Downey. The company even admits that “what you share and how you share it with” can say a lot about you — which is exactly the kind of insight AddThis sells its customers.

To opt-out of AddThis, click here.

This is just a sampling of some of the most troublesome trackers out there — and you may find others on the list below that are just as bad or worse. But this gives you an idea of what these types of companies are collecting about you.

To construct the list below, I visited the homepage of each website. It is possible that you will get different results if you are either logged in or logged out of a particular website, or if you visit different pages on that site. In other words, this is a very basic list, but it does provide a great deal of insight into who the companies are that float just beneath the surface of the Web to watch your every move.

1. Google Google 51. Yelp Facebook Connect

Google Adsense

Google Analytics

NetRatings SiteCensus

ScoreCard Research Beacon 2. Facebook Facebook

Microsoft Atlas 52. NBCOlympics.com Bizo

DoubleClick

Ensighten

Facebook Connect

Google +1

Krux Digital

NetRatings SiteCensus

Quantcast

ScoreCard Research Beacon

Twitter Badge 3. YouTube Dedicated Networks

Doubleclick 53. Content Moved (SecureServer.net) (none) 4. Yahoo! Yahoo! Ad Network

Comscore beacon 54. GoDaddy Google Analytics 5. Amazon Google Analytics

Comscore beacon

ShareThis 55. xVideos (NSFW) AddThis

Google Analytics 6. eBay Dedicated Networks

DoubleClick

eBay Stats 56. Outbrain (website marketing) ChartBeat

Google Analytics

New Relic 7. Craigslist (none) 57. Instagram Google Analytics 8. Wikipedia (none) 58. Etsy Facebook Connect

Google Analytics 9. Twitter Google Analytics

Twitter 59. NBC News Brilig

Cedexis Radar

ChartBeat

DoubleClick

DoubleClick Floodlight

Facebook Connect

Google Analytics

JumpTime

Krux Digital

Microsoft Atlas

NetRatings SiteCensus

Omniture

PubMatic

Pulse360

Pulse360 Notice

ScoreCard Research Beacon 10. Windows Live Live.com

Microsoft Advertising Network

Microsoft Atlas Technology

Microsoft Atlas 60. Adobe DoubleClick Floodlight

ForeSee

Omniture 11. LinkedIn Nielsen

Quantcast

Google Website Operator

Google Analytics

Netratings Site Census

ScoreCard Research Beacon 61. Target DoubleClick

DoubleClick Floodlight

DoubleVerify

ForeSee

Google Adsense

MediaMind

Microsoft Atlas

Omniture

RichRelevance 12. Blogspot Google Analytics 62. Pandora Facebook Connect

Google Analytics

NetRatings SiteCensus

ScoreCard Research Beacon 13. Bing Facebook Connect

Microsoft Advertising

Bing 63. Conduit Google Analytics 14. Go Audience Science

Dedicated Networks

Microsoft (Atlas Technology)

comScore VoiceFive

Google Adsense

Omniture

Revenue Science

ScoreCard Research Beacon

Doubleclick

Microsoft Atlas 64. CNet Audience Science

BlueKai

CBS Interactive

ClickTale

Crowd Science

DoubleClick

Facebook Connect

Facebook Social Plugins

Gigya Beacon

Gigya Socialize

Google +1

Google Analytics

New Relic

Twitter Button

Visual Revenue 15. MSN Facebook Connect

Twitter Badge

Microsoft Advertising

Microsoft (Atlast Technology)

AudienceScience

Microsoft Atlast

Comcast beacon

Revenue Science 65. Blogger Google Analytics

Google Friend Connect

Google +1

Facebook Connect

Twitter Badge 16. AOL 5Min Media

Advertising.com

LeadBack

Omniture 66. Indeed.com Google Analytics

ScoreCard Research Beacon 17. Pinterest Facebook Connect

Google Analytics 67. Hulu Bluelithium

Facebook Connect

Facebook Social Plugins

Google AdWords Conversion

Google Analytics

ScoreCard Research Beacon 18. Tumblr Google Analytics

Quantcast 68. Publishers Clearing House (pch.com) Gigya Socialize

Google Analytics 19. The Huffington Post Facebook Connect

Google+ 1

Twitter Badge

Google Analytics

Advertising.com

Omniture

Quantcast

Quigo AdSonar

ComScore VoiceFive

ScoreCard Research Beacon 69. Reddit Google Analytics 20. Netflix Microsoft (Atlast Technology) 70. Groupon Facebook Connect

Google Analytics

New Relic 21. CNN.com Audience Science

ChartBeat

DoubleClick

DoubleClick DART

Dynamic Logic

Facebook Connect

Facebook Social Plugins

InsightExpress

NetRatings SiteCensus

Omniture

Quigo AdSonar

ScoreCard Research Beacon 71. UPS WebTrends 22. PayPal Baynote Observer

Omniture 72. AT&T Acerno

Baynote Observer

ForeSee

Google Analytics

Meteor Solutions

WebTrends 23. Ask.com DoubleClick

Facebook Social Plugins

Google Analytics

ScoreCard Research Beacon 73. FOX Sports ChartBeat

DoubleClick

Microsoft Atlas

MSN Ads

NetRatings SiteCensus

ScoreCard Research Beacon

Tealium

Unica 24. ESPN ChartBeat

DoubleClick

Dynamic Logic

Dedicated Networks

Nielsen

ForeSee

NetRatings SiteCensus

Omniture

ScoreCard Research Beacon 74. The Pirate Bay Revenue Hits

Right Media

Zedo 25. Bank of America Coremetrics

Omniture

Omniture TouchClarity 75. Pof.com Google AdWords Conversion

Google Analytics

ScoreCard Research Beacon 26. AVG DSMM Advantage

Google AdWords Conversion

Google Analytics

Omniture 76. AWeber Systems AliveChat

AWeber

Google Analytics

Visual Website Optimizer 27. WordPress.com Google Analytics

Quantcast

Quantcast

Kiss Metrics

Optimizely

Comscore beacon

WordPress stats 77. Answers.com 5min Media

Facebook Connect

Facebook Social Graph

Google +1

Google Analytics

Quantcast

ScoreCard Research Beacon 28. Babylon.com Advertising.com

Tribal Fusion

Dedicated Networks (AppNexus)

Criteo

Google AdWords

Google Analytics

Tribal Fusion

AdNexus

LeadBack 78. BBC Audience Science

DoubleClick

Effective Measure

Google Adsense

NetRatings SiteCensus

Omniture

ScoreCard Research Beacon 29. The Weather Channel (Weather.com) Audience Science

Brightcove

DoubleClick

Facebook Connect

ForeSee

Google +1

Google Adsense

NetRatings SiteCensus

Nielsen

ScoreCard Research Beacon

Twitter Button

Visual Revenue 79. Searchnu.com eBay Stats

Google Analytics

ValueClick Mediaplex

ScoreCard Research Beacon 30. Chase Bank (Chase.com) [x+1]

BlueKai

Dedicated Networks

DoubleClick 80. Search-results.com ScoreCard Research Beacon 31. Comcast 24/7 Media

ForeSee

Quantcast

ScoreCard Research Beacon

Visual Revenue 81. RedTube (NSFW) BrandReach

DoublePimp

Google +1

Google Analytics

JuggCash

SexAdNetwork

TrafficJunky 32. Apple Omniture 82. U.S. Postal Service WebTrends 33. Zedo (ad network) Facebook Connect

Google +1

Google Analytics

Twitter Button 83. XNXX (NSFW) AddThis

Google +1

Google Analytics 34. Walmart 24/7 Media

Channel Intelligence

Omniture

Real Media

RichRelevance 84. Best Buy Advertising.com

BlueKai

Invite Media

Microsoft Atlas

Monetate 35. About.com (none) 85. Dictionary.com ClickTale

DoubleClick

Facebook Connect

Google Analytics

Legolas Media

NetRatings SiteCensus

Po.st

Quantcast

ScoreCard Research Beacon 36. Wells Fargo (none) 86. YouPorn (NSFW) DoublePimp

FriendFinder Network

Google +1

Google Analytics

JuggCash

Medley

TrafficJunky

Twitter Button 37. xHamster (NSFW) Adult Webmaster Empire 87. Match.com Adconion

Google AdWords Conversion

Google Analytics

interclick

LeadBack

Microsoft Atlas

XGraph 38. IMDB DoubleClick

Facebook Social Plugins

ForeSee

Google Analytics

ScoreCard Research Beacon

Twitter Badge 88. Salesforce.com AdRoll

AppNexus

Demandbase

Eloqua

Google AdWords Conversion

Omniture

Oracle Live Help

Quantcast 39. NYTimes.com AdSafe

Brightcove

ChartBeat

DoubleClick

Dynamic Logic

Facebook Connect

Google Adsense

NetRatings SiteCensus

New York Times

ScoreCard Research Beacon

WebTrends 89. Road Runner (rr.com) Advertising.com

DoubleClick

ForeSee

Gigya Socialize

Omniture

Quigo AdSonar 40. Microsoft Microsoft Atlas

MSN Ads

WebTrends 90. Washington Post Criteo

DoubleClick

Omniture

Quigo AdSonar

ValueClick Mediaplex 41. t.co (none) 91. Major League Baseball Disqus

DoubleClick

Facebook Connect

Omniture 42. LiveJasmin (NSFW) (none) 92. Drudge Report ADTECH

Brilig

eProof

Intermarkets

Lotame

Quantcast

Rubicon

ScoreCard Research Beacon 43. FoxNews.com AMP Platform

ChartBeat

Demdex

DoubleClick

NetRatings SiteCensus

Quantcast

Quigo AdSonar

ScoreCard Research Beacon

Visual Revenue 93. Capitol One [x+1]

DoubleClick Floodlight

Microsoft Atlas 44. PornHub (NSFW) DoublePimp

Google +1

Google Analytics

JuggCash

TrafficJunky

Twitter Button 94. Verizon Wireless BlueKai

DoubleClick Floodlight

Gomez

Microsoft Atlas

Monetate

Omniture

Turn 45. 302 Found (MyWebSearch.com) Google Analytics 95. USA Today Audience Science

Brightcove

DoubleClick

Facebook Connect

Google Adsense

Omniture

Quigo AdSonar

ScoreCard Research Beacon 46. GoogleUserContent.com (not directly accessible) 96. Photobucket AdMeld

Facebook Connect

ForeSee

Google Analytics

Lotame

Microsoft Atlas

NetRatings SiteCensus

PubMatic

RapLeaf

Rubicon

ScoreCard Research Beacon

SpecificClick 47. Flickr AdInterax

DoubleClick

ScoreCard Research Beacon 97. The Daily Mail AdMeld

Audience Science

BlueKai

DoubleClick

Google Analytics

Lotame

ScoreCard Research Beacon 48. eHow Audience Science

Chango

DemandMedia

Demdex

DoubleClick

Facebook Connect

Google +1

Google Analytics

Optimizely

ScoreCard Research Beacon

TargusInfo

Twitter Button

Tynt Insight 98. deviantART Google Adsense

Google Analytics

Quantcast

ScoreCard Research Beacon 49. optmd.com (none) 99. Zillow BlueKai

Google +1

Google Analytics

Right Media

ScoreCard Research Beacon 50. Imgur AddThis

Federated Media

Google Analytics

MixPanel

New Relic

Quantcast

Rubicon

Tribal Fusion

Zedo 100. MapQuest ADTECH

Advertising.com

DoubleClick

Facebook Connect

Facebook Social Plugins

Google Analytics

Omniture

ScoreCard Research Beacon

Twitter Button

In the spirit of full disclosure, here is the list for Digital Trends:

AppNexus

BrightRoll

ChartBeat

Facebook Connect

Google +1

Google Adsense

Google Analytics

LinkedIn Widgets

NetRatings SiteCensus

OpenX

Pinterest

ScoreCard Research Beacon

Twitter Button

This article has been updated with addition information.

Image via Petya Nikolova Petrova/Shutterstock

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