Online Advertising

Frequently Asked Questions

What Is It?
What is Interest-Based Advertising (sometimes called "online behavioral advertising")?

Interest-based advertising uses information collected across multiple websites to predict your preferences or infer interests and to show you ads that are more likely to be of interest to you. MORE ›

What is "personally identifiable information"?

Personally Identifiable Information (PII) includes name, address, telephone number, email address, financial account number, government-issued identifier, and any other data used or intended to be used to identify, contact, or precisely locate a person. The NAI Code provides disincentives to the use of PII for Interest-Based Advertising. As a result, NAI member companies generally use only information that is not PII for Interest Based Advertising and do not merge the non-PII they collect for Interest-Based Advertising with users' PII.

What is "non-personally identifiable information"?

Non-Personally Identifiable Information (Non-PII) is information that is not, on its own, used to identify, contact, or precisely locate a particular individual. Used for Interest-Based Advertising by NAI member companies, this data consists primarily of click-stream information (sites you have visited or links you have clicked) that, when using HTTP Cookies, is tied to a randomly generated anonymous identifier.

Is personally identifiable information used for Interest-Based Advertising?

As a general rule, Interest-Based Advertising does not depend on information that personally identifies you, such as your name, e-mail address, phone number, photographs, etc. Rather than using personally identifiable information, most Interest-Based Advertising that uses HTTP cookies uses random, unique numbers to match your web browser with interest categories. In some cases, personally identifiable information is used to bring interest categories online, but NAI member companies take measures to keep personally identifiable information separate from online browsing activities.

How Does It Work?
What are cookies?

A cookie is information (a small text file) that a site saves to your computer using your web browser. Cookies make the personalization of your web experiences possible. For example, a cookie may allow sites to record your browsing activities — like what pages and content you've looked at, when you visited, and whether you clicked on an ad. Cookies can help sites remember items in your shopping cart, your log-in name, your preferences such as always showing the weather in your hometown, or your high game scores. Other cookies may be placed in your browser by third-party advertising companies to help deliver the ads you see online. These "third-party cookies" may be used to “remember” parts of your online activities in order to deliver ads tailored to your interests. For example, if you read an article online about running, a cookie may be used to note your interest in running. As you continue to surf the web, you may see coupons to save money on running shoes. Cookies are not spyware or adware, and can’t deliver viruses or run programs on your computer.

Some NAI members may start using non-cookie technologies for Interest-Based Advertising. The NAI has published its Guidance on the Use of Non-Cookie Technologies for Interest-Based Advertising and is currently working with members during an implementation period to ensure that new business models and the use of non-cookie technologies are implemented by NAI members in a manner that is consistent with this Guidance. During this implementation period, however, while some members may start using non-cookie technologies for Interest-Based Advertising, the current NAI opt-out tool does not indicate when members use non-cookie technologies for Interest Based Advertising. To learn more about this Guidance, and how to opt out of non-cookie technologies, visit our FAQ’s on Non-Cookie Technologies

What are “third-party” cookies?

The term "third-party" indicates that rather than having a direct relationship with a user, a company has a relationship with one or more of the websites that a user visits.  For example, if a user visits sportsfan.com, that website is the "first party."  If sportsfan.com partners with an advertising network, platform, or exchange to place ads, the network, platform, or exchange is the "third party."  The advertising network uses cookies when the user visits sportsfan.com to help it select and serve the best ad. These cookies are considered "third-party cookies."  First parties partner with third parties in this way because third parties have technology and expertise to enable more efficient ad placement across websites.  NAI members, working with brands, publishers and websites, use third-party cookies to make advertising more engaging and relevant to users and more valuable to publishers and advertisers.

What are web beacons (sometimes called “pixels” or “web bugs”)?

The short answer – a Web beacon enables two websites to share information. Generally, a web beacon consists of a small piece of software code, just like the other code that makes up a web page, and that incorporates a graphic image on a web page or email. There may or may not be a visible graphic image associated with the web beacon, and often the image is designed to blend into the background of a web page or email. Web beacons can be used for many purposes — including site traffic reporting, unique visitor counts, advertising auditing and reporting, and personalization.

Who is doing Interest-Based Advertising? Who are NAI Members?

Many of the banner ads displayed on web pages are not selected and delivered by the websites you visit, but by third-party advertising companies that manage and provide advertising for numerous unrelated websites. Websites work with third-party advertising companies because these companies can more efficiently sell advertising space. This enables the websites to make more revenue and continue providing free content and services. Some of these companies, which we refer to as "third-party ad networks,” or “third-party ad companies,” join NAI to signal their adherence to privacy best practices and to provide a means for consumers to opt out of Interest-Based Advertising on the NAI website.

What is a non-cookie technology (sometimes called a "statistical identifier")?

The online experience is constantly getting richer, more informative and more responsive to a user's needs. While browsers have controls to help users manage how cookies affect their experience, cookies are only part of the story. Some of these technologies we call "non-cookie" technologies because usual browser controls are designed with cookies in mind, not non-cookies.

An example of a non-cookie technology is a statistical (or probabilistic) identifier. Such an identifier is the result of a computation about a browser or device that companies rely on to tailor their online advertising. Instead of placing a cookie on a browser, and then reusing the value inside of the cookie to identify the browser, companies hope to identify a browser or device by using data about the browser or device to compute a value. Non-cookie technologies operate differently and could be used for a variety of purposes. These could include ensuring your online banking stays secure, preventing online shopping fraud, or serving you the right online advertisements.

What Are My Options?
What choices do I have regarding Interest-Based Advertising?

Consumers have a variety of options available to customize their web experience regarding the use of HTTP cookies on your browser for Interest-Based Advertising, ranging from browser controls and add-on utilities to opt-out tools. Learn more about those options.

How do I know which NAI member companies have placed cookies on my computer?

The NAI opt-out tool automatically scans your computer to look for Interest-Based Advertising cookies set by each of our member companies. Simply go to the opt-out page to check your browser.

How does the NAI opt-out tool work?

The NAI opt-out tool reports which NAI member companies have placed a cookie that can be used for Interest-Based Advertising on your browser by checking for the presence of such cookies and reporting back whether it found any “active” cookies. The NAI opt-out tool also allows you to set cookies that will tell NAI members you do not want to participate in Interest-Based Advertising. The tool does not delete individual cookies nor does it necessarily replace other cookies delivered by NAI companies, such as those that are used for ad reporting or ad serving purposes that, for example, allow advertisers to change the sequence of ads, as well as to track the number of ads delivered.

Please Note:  Technology used to deliver interest-based advertising continues to evolve and change.  As of the date of publication of this page, this opt out covers interest-based advertising delivered to your device via HTTP cookies only.  It does not cover the use of other technologies that NAI member companies may use to deliver interest-based advertising. NAI and its members are currently working on developing a mechanism to allow you to opt out of the use of non-cookie technologies for Interest-Based Advertising by NAI members. NAI is working with its members during an implementation period to ensure that new business models and non-cookie based technologies are implemented by NAI members in a manner that is consistent with the Guidance on the Use of Non-Cookie Technologies for Interest-Based Advertising.

Will I ever need to renew my opt-out choices or opt out again?

If you opt out of Interest-Based Advertising by one or more NAI member companies where they are using HTTP cookies, that choice will be stored in “opt-out cookies.” The NAI requires that such opt-out cookies have a “lifespan” of at least 5 years. However, if you ever delete opt-out cookies from your browser (such as by clearing all cookies), buy a new computer, or change web browsers, you'll need to renew your opt-out choices. NAI member companies need to be able to read an "opt-out" cookie on your browser to know not to collect and use data for Interest-Based Advertising purposes. You can also check the status of your opt-out choices from the NAI opt-out page at any time. To help prevent the accidental deletion of your opt-out choices, learn more about the DAA's Protect My Choices opt-out protector utility.

You will also need to update your choices once the opt out tool covers the use of other technologies that NAI member companies may use to deliver interest-based advertising. NAI and its members are currently working on developing a mechanism to allow you to opt out of the use of non-cookie technologies for Interest-Based Advertising by NAI members. NAI is working with its members during an implementation period to ensure that new business models and non-cookie based technologies are implemented by NAI members in a manner that is consistent with the Guidance on the Use of Non-Cookie Technologies for Interest-Based Advertising.

Can my browser settings interfere with the use of the NAI opt-out tool?

Your browser must be set to accept third-party cookies in order for the NAI opt-out tool to work.

Attention Safari users: Apple presets the Safari browser to block cookies from sites other than those you visit directly. As a result, the NAI opt-out tool, which uses third-party cookies, generally will not work on browsers left in this default setting. If you are using Safari and wish to use the NAI’s opt-out tool, you can change your cookie settings to allow all cookies and then use the NAI opt-out tool. Opt-out cookies for the selected NAI member companies can then be placed on your computer or device. You can change your cookie settings back after completing this action, if desired.
Having problems?

Attention Internet Explorer users: Yahoo! has a security path that allows Internet Explorer to block its ad network (third-party) cookies when a user's browser privacy setting is set to "Medium High" or "High." As a result, the NAI opt-out tool, which uses third-party cookies, cannot place Yahoo!’s opt-out cookie for browsers that use this setting at this time. For more information on changing your IE browser settings click here.
Having problems?

Will I still get ads if I opt out using the NAI tool?

Yes. Opting out of Interest-Based Advertising by one or more NAI member company using the NAI opt-out tool stops those companies from engaging in Interest-Based Advertising for your browser. You will still see ads, some of which may be delivered by NAI member companies. However, because the NAI member companies from which you have opted out will no longer use Interest-Based Advertising data to target those ads to your computer, the ads may be less relevant.

Will using the NAI opt-out tool automatically delete all of an NAI member's cookies from my computer?

Not necessarily. Some NAI members offer services that are unrelated to Interest-Based Advertising, and others place cookies on your browser for purposes such as ad delivery and reporting, fraud prevention, and limiting the number of times you see an ad. Opt-out cookies signal to NAI member companies not to tailor ads based on information collected across websites, but may leave the cookies used for other purposes in place.

What do I do if I have a problem with the opt-out tool?

If you encounter technical difficulties while trying to opt out, we ask that you first try again.

If you continue to experience problems, please visit our support page.

What do I do if I think an NAI member has violated the NAI Code?

Please contact NAI staff!

We rely in part on consumers to help identify possible violations by NAI members of the NAI Code.
Click here to file a complaint about a member.

Your Privacy & Personal Information
Does the NAI opt-out stop spam, junk mail, or pop-ups?


The NAI opt-out tool covers only member companies’ use of cookies to target advertising based on users’ web browsing.

We do not maintain opt-out programs for postal or electronic mail, text messages, or for pop-ups.
For more information about controlling spam and email preferences visit the FTC website.

Can Interest-Based Advertising information be used for non-marketing purposes?

NAI members and the online advertising industry as a whole have also pledged not to use information gathered for Interest-Based Advertising to decide if you’re eligible for employment, health insurance, or credit. In fact, the NAI prohibits its companies from using this information for any non-marketing purposes.

Is ID theft a risk of Interest-Based Advertising?

Online advertising served by NAI members is not a source of identity theft. Your social security number or credit card number aren’t being used to show ads. Being placed in the interest categories and audience groups used to make ads relevant does not increase your risk of identity theft.

However, it is important to be vigilant when you are online – learn more about how to protect yourself and your data against ID theft here and here.

Are viruses and spyware a risk of cookies?

No. Cookies are not software, and cannot run as programs on your computer. Cookies cannot read or examine the data on your computer or alter its settings in any way. Still, you should always take precautions to ensure your devices are protected. More information about computer security.

Do these FAQs address every business practice and technology used by NAI member companies?

Our goal is to share information about some common ways that NAI members engage in interest-based advertising. Through brief, easy-to-read summaries and simple diagrams, we hope to teach consumers how interest-based advertising generally works when a user visits a website. We don't cover every variation in business practices, nor do we cover mobile, and, given how rapidly technologies change, we can’t promise that the site will always reflect the latest techniques used for interest-based advertising.  Please check back for updates as we add more information. To submit feedback on our site, please click here.