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Targeted Advertising and Cookies

 Targeted Advertising and Cookies (PDF, 191 KB)

What is Targeted Advertising?

Advertising companies can track your online activities, across different websites and over time, in order to build a detailed personal profile about you. This profile is used to help the companies learn about you, and to display advertisements on your screen targeted specifically to your interests. In most cases, this happens without your knowledge, and unless you have taken affirmative steps to prevent it, you are likely subject to targeted advertising now. Advertising in this way raises significant privacy concerns. Profiles are supposed to be anonymous, but the detailed content, when compiled and analyzed together, can be used to identify you with relative ease.

Can I Stop Targeted Advertising?

Companies use different techniques to collect information about you; some techniques are more easily prevented than others. The most comprehensive protection requires installing special tools, but you can adjust your browser settings to ensure at least some protection. Third-party cookies are often used for targeted advertising and can be blocked by following the instructions in the table below.

What are Cookies?

A cookie is a small string of text. It is placed automatically on your local hard drive by a website, and is only retrievable by that same website. A cookie will typically include a unique identifier which is used to label your computer. Some cookies may be useful to you because they help a website remember your login information, language, and geographical location. Deleting cookies will result in the loss of your saved passwords and preferences. Blocking all cookies will prevent you from accessing many websites and is not recommended.

What are Third-Party Cookies?

Targeted advertising is done with third-party cookies. If you visit a website and there is an ad embedded in the page by an advertising company, a third-party cookie with a unique identifier will be saved automatically on your hard drive. This is in addition to the regular cookie you will receive from the website itself. If you then leave and go to a second website and there is an ad from the same advertising company, the company will recognize you based on your unique identifier. The advertising company will link together your browsing activities from both websites and build a profile about you. If the advertising company repeats this with enough websites, the profile can become quite detailed. You can set up your browser to block only third-party cookies but allow other cookies by following the instructions below.

Chrome Safari
  1. At the top right corner, click on the icon that looks like three dots in a vertical line.
  2. Click Settings.
  3. At the bottom, click Show Advanced Settings.
  4. Under the "Privacy" heading, click Content Settings.

a. To Delete Existing Cookies:

  • Click All cookies and site data.
  • Click Remove all.

b. To Block Future Third-Party Cookies:

  • Under the "Cookies" subheading, check the box next to Block third-party cookies and site data.
  1. At the top left corner, click Safari.
  2. Click Preferences.
  3. Click Privacy.

a. To Delete Existing Cookies:

  • Click Remove All Website Data.
  • Click Remove Now.

b. To Block Future Third-Party Cookies:

  • Beside the "Block cookies" subheading, select Allow from websites I visit.
Internet Explorer Firefox
  1. At the top right corner, click on the Tools icon that looks like a gear.
  2. Click Internet Options.

a. To Delete Existing Cookies:

  • Go to the General tab. Click Delete...
  • Check the box beside Cookies and Website Data. Click Delete.

b. To Block Future Third-Party Cookies:

  • Go to the Privacy tab. Click Advanced.
  • Under the "Third-Party Cookies" heading, select Block.
  • Click OK. Click OK again.
  1. At the top right corner, click on the Open Menu icon, which looks like three horizontal lines.
  2. Click Options.
  3. One the left, click Privacy.
  4. Under the "History" heading, click on the drop-down arrow. Click Use custom settings for history.

a. To Delete Existing Cookies:

  • Click Show Cookies..
  • Click Remove All.

b. To Block Future Third-Party Cookies:

  • Beside "Accept third-party cookies", click the drop-down arrow. Click Never.

For more information, see the .