UPenn study: 91% of health related webpages relay sensitive info to third parties including Google, Facebook and data brokers like Experian.
Adam Rifkin stashed this in Facts
They call this the Invisible Web:
The recent study "Privacy Implications of Health Information Seeking on the Web" conducted by Tim Libert at the Annenberg School for Communication (University of Pennsylvania) shows that we have a for more nonchalant attitude regarding health privacy when it comes to personal health information on the internet.
Libert analyzed 80,142 health-related webpages that users might come across while performing online searches for common diseases. For example, if a user uses Google to search for information on HIV, the Center for Disease Control and Prevention (CDC) webpage on HIV/AIDS (http://www.cdc.gov/hiv/) is one of the top hits and users will likely click on it. The information provided by the CDC will likely provide solid advice based on scientific results but Libert was more interested in investigating whether visits to the CDC website were being tracked.
He found that by visiting the CDC website, information of the visit is relayed to third-party corporate entities such as Google, Facebook and Twitter. The webpage contains "Share" or "Like" buttons which is why the URL of the visited webpage (which contains the word "HIV") is passed on to them – even if the user does not explicitly click on the buttons.
Libert found that 91% of health-related pages relay the URL to third parties, often unbeknownst to the user, and in 70% of the cases, the URL contains sensitive information such as "HIV" or "cancer" which is sufficient to tip off these third parties that you have been searching for information related to a specific disease.
Most users probably do not know that they are being tracked which is why Libert refers to this form of tracking as the "Invisible Web" which can only be unveiled when analyzing the hidden http requests between the servers. Here are some of the most common (invisible) partners which participate in the third-party exchanges:
This is absolutely atrocious.
This is the reason that Google, Facebook, and Twitter are free to use.
I think that most people are not even aware that those companies do this.
Great comment by Redditor gpennell:
Tired of this kind of thing?
How to greatly improve your browsing privacy in about 10 minutes
If you aren't using Firefox, do so.
Install these Firefox addons: Disconnect, uBlock Origin, Random Agent Spoofer, Self-Destructing Cookies, and HTTPS Everywhere. Note that Self-Destructing Cookies will sign you out of everything when you install it. You'll have to log back in every time unless you whitelist the site.
Set your default search engine to DuckDuckGo. When you need Google, add "!sp" before your DuckDuckGo searches to send your searches through StartPage, which acts as a Proxy to Google. You'll get Google's results with none of the tracking.
Quickly and easily enhance your privacy in other areas of your lifeStart using TextSecure and RedPhone if you're on Android, or Signal if you're on iOS. Signal can exchange messages with TextSecure users and phone calls with RedPhone users. "But what about other private messenger apps?" No. use TextSecure and Signal, and get your friends to use them too.
Critical: Learn how to do passwords properly. I don't care about your special "password algorithm" or whatever for remembering passwords on different sites. If the password came from your head, it's wrong.
Use a VPN service. Cryptostorm is a good choice. Here is a good list with more. The provider can still technically see your traffic, but these all claim to not keep logs. Compare with your ISP, who readily admits to logging everything you visit and sharing it with advertisers.
Go deeper and really defend yourself (and everyone)
Doing just the above will substantially reduce your trackability, but will not totally protect you. Continuing from here gets more nuanced, but is incredibly worthwhile if you value your privacy or take issue with living in a society that relies so heavily on surveillance.
Check out Privacytools.io for an extensive list of privacy resources, including VPNs, browser extensions, encryption tools, and more.
Take a look at the Electronic Frontier Foundation's Surveillance Self-Defense for primers, tutorials, and guides on how to enhance your privacy online.
For that matter, learn about the Electronic Frontier Foundation.
Join a local Cryptoparty to learn how to use electronic privacy tools and to meet other people who are enthusiastic about fighting mass surveillance and other invasions of privacy. (Disclaimer: I run a local Cryptoparty.)
Use the Tor Browser Bundle. Make sure you read the warnings so you'll know how to not screw up your anonymity. Tor works better when more people use it, for a multitude of reasons. You are promoting freedom simply by using the Tor Browser.
Feeling more adventurous, needing more security, or wanting more privacy? The Tor Browser Bundle is great, but is only as safe as the operating system it's running on. Tails is a Linux-based distribution that routes all traffic for the whole OS through Tor, which means that your browsing will be anonymous, even if something exploits the browser and breaks out into your OS. Again, this is entirely dependent upon using it correctly.
Switch to Linux.
Join us over in /r/privacy for more resources.