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What Is Personally Identifiable Information, and Why Is It Important?

Where Do I Go To Learn How Companies Treat My Information?

What Can I Do To Protect My Information Online?

Cookies and Online Tracking

Using Social Networks & Photo-Sharing Services

Mobile Devices & Privacy

Additional Privacy Considerations

Online Privacy Rights under Maryland and Federal Law

This guide was created in collaboration with
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Printable version of this Guide (PDF).

Cookies and Online Tracking


In addition to collecting PII, companies also may collect other information about your computer or device behind the scenes. For example, as you surf the Internet using a web browser, sites can place "cookies" on your computer. A cookie is a small file that allows a website to store data about your browsing activities, including identifying the pages and content you've looked at, when you visited, what you searched for, and whether you clicked on an ad. Cookies can be used to help websites remember things like which items you place in an online shopping cart, or your log-in information or preferences for future visits. Cookies can also be used to create a profile of your online activities so that companies may deliver ads tailored to your interests. While some people may like having ads tailored to their interests, others may find such targeted advertising undesirable or intrusive. characters with tools in hand and browser logos as faces

There are a number of steps that you can take to control the cookies placed on your computer, or to opt out of targeted advertising:

  • Use Your Web Browser Tools and Controls. Many browsers have different ways that you can delete cookies or limit the kinds of cookies that can be placed on your browser. For example, look under "Tools" or "Safety" in your browser for settings like "Options" or "Privacy," and review what controls and deletion options are available. Some browsers also permit you to install plug-ins or add-on tools that can block, delete, or control cookies.

    Many browsers also offer "private browsing" tools so that your online browsing can be kept hidden from other people who use the same computer. When these features are turned on, your browser typically won't keep cookies, browsing history, search records, or the files you download. These tools are not the same across all browsers, so it is important that you check to see what kind of data your browser stores.

  • Do Not Track Features. Browsers provide users with "Do Not Track" settings, but how web sites respond to this signal is not yet standardized. For more information about the developing Do Not Track standard and how companies will treat your choices, visit www.allaboutdnt.org.
  • Consider Opt-Out Cookies. A number of advertising networks and other companies that set third-party cookies on browsers offer consumers the ability to opt out of receiving these cookies and the targeted ads they enable. For example, programs from the Digital Advertising Alliance and the Network Advertising Initiative offer tools for opting out of targeted advertising - typically using cookies - for their members. These ad networks will still collect data and deliver the ads you see, but those ads won't be selected based on a profile on your web surfing. Just remember that if you delete all your cookies, you will delete your opt-out cookies as well, and will have to go through the procedure again to restore your opt-out cookies.

Note that cookies are just one tool used by third parties to track you online. Other tools include web beacons (also known as "web bugs" ), pixel tags, and device fingerprinting. These tracking tools may provide you benefits, like more relevant ads and more convenient online experiences, but remember that, unless you have taken affirmative steps to reduce or prevent tracking, your browsing will likely be tracked in some way. (For more information on tracking, see the section entitled "Mobile Devices & Privacy. " )


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