A tag (also referred to as a pixel or beacon) is a tiny snippet of code inserted into website content that is used to collect data related to a website visit. Similar functionality is enabled in a mobile app through the use of an SDK (Software Development Kit). Tags and SDKs allow a website operator or application developer to customize and categorize information that is collected. Tags and SDKs can be used for many purposes including site and app usage analytics, audience measurement, and content and advertising personalization.


Quantcast provides Quantcast Tags and the Quantcast SDK to our partners. Our partner website operators integrate the Quantcast Tags on their webpages. Partner mobile application developers integrate the Quantcast SDK with their applications. When a user views a partner’s site, or uses a partner’s app, information (such as IP address) is sent from the browser or mobile device to our servers. The tag also enables Quantcast to set a cookie in the browser.


Cookies are values stored in the browser related to website visitation. Cookies allow a website to recognize a browser and are commonly used to store user preferences or identifiers. Some cookies are set by the website that a browser visits (known as first-party cookies), and others are set by that website’s partners (known as third-party cookies) which may include Quantcast. Cookies can expire at the end of a browser session (known as session cookies) or they can be stored longer (known as persistent cookies). Quantcast’s persistent cookies expire within 13 months, except for our Opt-Out cookie. Our Opt-Out cookie expires in 10 years and allows us to remember your opt-out choice.


Collectively, Quantcast tags, SDKs, and cookies enable Quantcast to measure and understand interactions with websites and apps, so that we can provide insights to website and app owners about how their websites and apps are being used. These insights also enable Quantcast to help website and app owners and marketers to provide more relevant advertising and content and to measure users’ interaction with such ads and content.


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Quantcast collects information sent to us by browsers that encounter our Tags, including, for example, browser type, browser time, time of access, screen resolution, IP address, referring site URL, current site URL, and search strings. Some information that Quantcast collects is configured by website publishers. The table below summarizes information Quantcast may receive from browsers:

Parameter (Example) Description
r=288408424 Random number that prevents the browser from using cached data instead of contacting Quantcast’s servers
a=p-bcLY1rnM-2- Publisher’s unique Quantcast Measure ID (unique to the publisher, not the browser)
fpan=0 True/false field for indicating whether the first party cookie was newly set on this request
fpa=P0-637818636-1294088227693 A value of a first party cookie value set in a non-Quantcast domain such as a publisher’s domain; the first-party cookie appears in the browser as a cookie named “__qca”
mc=5bb75135-bd606-808bc-f1290 A value of a third-party cookie set in the quantserve.com domain which is a domain managed by Quantcast; the third-party cookie appears in the browser as a cookie named “mc”
d=EE8BcwGtGoEAs9-TDCo774OTmYcMv7AL73ori6KSyKwsPt4bOfTBn5I8n1fugPyNEOzCgu2OHBwJ7wv6ggACYbvGwgGOxIwMJ9V6eLnbnqK-_HbFcsC8gQbFcsC5cGxXLAuYIGxXLAvplqnPI2AzFoA A value of a third-party cookie set in the quantserve.com domain. The value of this cookie is a compact encoding of the mc cookie’s membership in retargeting segments and information about third-party partners of Quantcast, such as advertising exchanges. The third-party cookie appears in the browser as a cookie named “d”
ns=0 True/false field for whether the pixel is firing from the top level window (i.e., this answers the question: is the pixel firing from inside an iframe?)
ce=1 True/false field for whether cookies are enabled in the browser
je=1 True/false field for whether javascript is enabled in the browser
sr=1920x1200x24 Screen resolution
enc=n Does the browser support URL encoding for ref, url, and ogl parameters?
dst=1 True/false field for whether daylight savings is in effect
et=1348600176786 Unix timestamp
tzo=240 Time difference in minutes between UTC time and local time
ref=http%3A%2F%2Fm.kotaku.com Encoded referring URL
url=http%3A%2F%2Fm.kotaku.com%2F5985087 Encoded URL of page where pixel fired
ogl=image.http%3A%2F%2Fcache%252Ekotaku%252Ecom%2Fassets%2Fimages%2Fimg%2F18f4logogda2xjpg%2Ffb%252Ejpg%2Ctitle.

Encoded ogl data

This refers to Facebook’s Open Graph Data. It reflects website customizations that enable the publisher’s website integration with Facebook.
labels=event.sports
labels=“Author.John Doe”
Publisher-configured labels to segment the audience
event=load The type of browser event that caused the pixel to fire. Load refers to page load. Other common examples are refresh and click events.
rf=0 Rule Fetch status indicating if publisher-configured rules have been fetched from Quantcast
cm= TRUSTArc Consent Manager status (may be blank)
source=tealium Name of a publisher’s tag manager integration, if applicable
gdpr_consent= General Data Protection Regulation (“GDPR”) consent string, if applicable. This parameter may be sent from your browser after receiving consent from a Consent Management Provider. If no consent string exists (if GDPR does not apply, for instance), this parameter is absent
gdpr=0 A “1” Indicates that GDPR applies to the request; a “0” indicates that it doesn’t apply
qjs= Indicates that the pixel request was initiated by a script (as opposed to an image-based pixel, for instance)


If you choose to opt-out of our services, Quantcast will set a third-party “opt-out” cookie on your browser. The “opt-out” cookie will appear as “qoo” in the quantserve.com domain. The value of the “qoo” cookie will be set to a non-unique value, such as “OPT_OUT”. The presence of the cookie in your browser tells us you have opted-out. For more information on opting-out, please consult our opt-out page here. The only way we know if your browser has opted out is by the presence of the “qoo” opt-out cookie. If you delete this cookie, we will not know that you have opted out, and will no longer treat your browser as an “opted-out” browser. After you have opted-out, other cookies may remain in your browser, such as the “d” cookie (described above). When you opt-out, the d-cookie is set to a value that removes your cookie from some retargeting lists. Other cookies, such as first-party cookies, set in the publishers’ domains, may also remain in your browser.

Under European privacy law, personal data is any data that is or can be associated to an individual (such as a website or app user) enabling that individual to be singled out. For example, personal data includes ‘identified’ personal data such as names, usernames, passwords and contact information. It also includes ‘identifiable’ data such as online identifiers like cookie identifiers, device IDs and IP addresses.

As online identifiers are considered personal data in most contexts, Quantcast may, for the purposes of European privacy law, be regarded as collecting the personal data of website and app users on websites and apps using Quantcast tags, SDKs, and cookies. For our business partners, Quantcast may also collect certain personal data such as names, addresses, and other contact details. However, when it comes to website visitors and app users, Quantcast sets and collects random unique identifiers (such as random unique identifiers that we set as cookie values, also called cookie identifiers) and not actual names or contact details. For more information on Quantcast’s privacy practices, visit our Privacy Policy.

Under the laws of countries outside of Europe, Quantcast may not always be regarded as collecting personal data.


Quantcast uses the information collected via the Quantcast tags, SDKs, and cookies to provide the Quantcast Measure and Advertise products.

The Quantcast Measure product helps website and app owners to understand the characteristics and demographics of the people who visit their sites and use their apps. The Quantcast Advertise product allows businesses to deliver relevant online advertising to individual users. For companies that want to advertise online, the Advertise product helps get their ads in front of the people that are most likely to find them interesting. This is also helpful to users who are provided with ads that are most useful and relevant to their interests.


We have aspired to build the Quantcast Measure and Advertise products with privacy principles such as the data minimization principle in mind, and we are committed to being transparent with users about how we collect and process their personal information.

We have a comprehensive privacy policy outlining how we process personal data that we make available to users and how we provide individuals with choice and control over personal data. You can consult the Privacy Policy here.


In short, under European privacy law, the controller is the party who determines the “why” and “how” of the processing of personal data. The controller controls and is responsible for this data. An example of a controller is an employer who controls personal data about its employees.

On the other hand, a processor merely holds or processes the personal data on the instructions of the controller. The processor does not exercise responsibility for or control over the personal data. An example of a processor would be a payroll company that processes employee payroll data on behalf of an employer (controller), but has no ability to use the data for any other purposes.


The complexity of the audience measurement and real-time advertising business means that it can often be difficult to identify the role that each actor plays. However, for the purposes of European privacy law, the determining factor in identifying a controller will be the factual reality surrounding the processing of the personal data.

In providing the Measure and Advertise products, generally Quantcast is acting as the controller of any personal data it processes as it generally determines the “why” and “how” of processing.

For example, for data processed by each of these two products, Quantcast designs the cookie that is set and determines both the cookie’s expiration date and how the cookie operates. In addition, when we receive data via cookies and tags, we use that data to train our algorithms to improve our services generally. Therefore, Quantcast is the controller of the data it collects via its cookies.

Our partners such as website operators and mobile application developers are considered autonomous controllers insofar as they collect personal data from users for their own purposes. We do not jointly control the personal information collected via the Measure and Advertise products with our partners.


To the extent that Quantcast acts as a controller of personal data collected by the Measure and Advertise products, we are responsible for upholding data subjects’ rights as they may apply in accordance with European privacy laws. Under such laws, data subjects may have a number of rights including the right to access their data, to obtain it in an easily accessible format, or request deletion of their data. We uphold these rights where they apply in accordance with our Privacy Policy.


For more information on Quantcast’s privacy practices, visit our Privacy Policy.