Data Types & Identifiers

Third-party cookies

User data that is passed from a web browser to an ad server. This information can be used to recognize return site visitors and track users across websites. Google Chrome, used by 63 percent of people worldwide, is the last major browser to support third-party cookies. Google announced in 2020 that it would eliminate third-party cookies from Chrome by 2022, but on June 24, 2021, the company revealed plans to postpone the end of third-party cookies to late 2023.

First-party cookies

The web browser data that is collected directly by a site operator. First-party cookies convey the same data as third-party cookies but are controlled by the brand or site and so can be connected to first-party data like a customer‘s name, credit card number or email address, using internal tools like customer relationship management (CRM) platforms or customer data platforms (CDPs), which bring disparate sources of data together to create a unified profile of each customer that can be accessed by other systems.

Zero-party data

Data that a consumer provides directly and deliberately to a business, such as when customers fill out surveys or offer their email or phone number for follow-up communications. Many brands and organizations categorize zero-party data as first-party data, while others consider it a subset of first-party data.

First-party data

Data that is collected by a brand or business when it directly interacts with its audience, customers or users. First-party data is owned by the brand, which has legal responsibilities for storing and using the data in secure, privacy-safe ways.

Second-party data

First-party data that is collected by one company and shared with a second company for marketing purposes, usually to enrich their own data, glean insights or increase scale. Publishers including The New York Times, Meredith, Condé Nast and CafeMedia use second-party data solutions to compare their readership data with an advertiser‘s first-party data so that the brand can personalize campaigns for known customers or measure lift among a trackable online audience. Other common use cases include retailers and CPG brands sharing data to target known customers or an airline and hotel brand joining datasets to personalize travel offers.

Third-party data

Data collected or purchased by data or technology companies, often using third-party cookies, which can be aggregated and resold in anonymous datasets. Third-party data is commonly used for online advertising and marketing measurement.

Shared ID / Universal ID

Identifiers used by programmatic media and advertisers to target users across the open web. Shared IDs or Universal IDs are embraced primarily by advertising tech companies — demand-side platforms, supply-side platforms and ad servers — as a way to scale their user-level targeting and attribution to compete with walled garden platforms. These shared IDs primarily rely on third-party cookies but must transition to persistent identifiers like email addresses.

Identity resolution providers

Data vendors that onboard identity data and match IDs between advertisers and publishers. LiveRamp is the best-known example, though the category ranges from startups such as Zeotap and Throttle to decades-old consumer data companies like TransUnion and Neustar. These companies, which used third-party cookies to match IDs for online advertising and analytics, are transitioning to email-based identity systems.


Apple‘s Identifier for Advertising (IDFA) is used by app developers and mobile marketing companies to track users in its app ecosystem. In an update to iOS 14 in April 2021, Apple made IDFA opt-in for all users, allowing people to block or permit specific apps from collecting or using the IDFA.


Apple‘s Identity for Vendors (IDFVs) allows app developers to track activity across multiple apps owned by the same company, such as Facebook and Instagram. Apple has been encouraging companies to migrate to IDFV as an alternative to IDFA. This has spurred some industry deals, such as Zynga‘s acquisition of Chartboost, which would enable the company to employ the same ID for its owned-and-operated games as well as apps that use Chartbook‘s ad monetization tools.


Mobile Ad IDs (MAIDs) have historically been used for ad campaign attribution on an individual user level. These IDs are under the threat of becoming ineffective the more people opt out of ad tracking on Apple devices thanks to the IDFA opt-in rollout. MAID is a generic term that encapsulates IDFA, IDFV and GAID.


Google Ad IDs (GAIDs) are essentially the Android equivalent of Apple‘s IDFAs. Like Apple, Google is encouraging app developers, advertisers and publishers to find other, more privacy-focused means of tracking mobile ad campaigns on its devices. There is much industry speculation that Google could follow Apple‘s lead in making tracking via GAID opt-in by default.

Privacy Sandbox

Google‘s Privacy Sandbox

The product development and testing toolkit Google is using to evaluate privacy-safe, data-driven advertising strategies in Chrome in preparation for when the browser deprecates third-party cookies in late 2023. The Privacy Sandbox seeks to create methods to use first-party data and aggregated browser metadata to replace user-level third-party cookies for ad targeting, attribution and frequency capping, among other capabilities.


Google‘s Privacy Sandbox framework for bidding on ads in Chrome is called TURTLEDOVE (“Two Uncorrelated Requests, Then Locally-Executed Decision On Victory”). This will move the ad auction from running on servers to being fully conducted within the browser. Specifically, it allows for advertisers to run retargeting campaigns but by using advertiser-defined cohorts rather than user tracking via third-party cookies. The first product test using the TURTLEDOVE framework is called FLEDGE (“First Locally-Executed Decision over Groups Experiment”) and is planned to run this year. The idea with FLEDGE is to test industry proposals for TURTLEDOVE, such as having trusted servers operate the real-time ad auction instead of the browser itself.


The acronym for Federated Learning of Cohorts, a method for targeting online users and measuring campaigns by aggregating individuals into groups with similar online behaviors. Google promotes the idea as a solution for cookieless performance measurement and behavioral targeting.


The acronym for First Locally-Executed Decision over Groups Experiment. It is a simplified version of TURTLEDOVE and intended as a steppingstone toward a solution that is more privacy-preserving.

Measurement & Attribution


Apple‘s privacy-first method for attributing app installations to mobile app ad campaigns. Apple registers a conversion and passes the result to the advertiser and app developer but doesn‘t include user-level or device ID information.


Private Click Measurement is a new Safari feature that tracks click-based attribution from app to desktop without user-level cross-site tracking. Safari silently registers cross-site sales or sign-ups generated by an ad and then sends an attribution report with aggregate conversion data.

Redirect Tracking

When people visit a site or are linked from one site to another, redirect tracking is a way for companies to insert a separate domain that is briefly visited by the user before they‘re directed to the main page. Adtech vendors use redirect-tracking pages to target ads and monetize users on other sites on behalf of retailers or online sellers. Safari and Firefox block this tactic, but it is still enabled on Chrome until it deprecates third-party cookies in 2023.

Attribution Reporting API

A proposed attribution technique that would be built into Google‘s Chrome browser. The idea behind this product, which until 2020 was known as Conversion Measurement API, would be to preserve the ability of advertisers to measure the impact of individual elements of ad campaigns and assign credit to specific sites, apps or channels without using any individual consumer information. This API would complement Google‘s post-cookie push to use cohorts of users for targeting rather than any personally identifiable data.


Mobile measurement partners are ad attribution companies that integrate with apps to serve targeted ads or track campaign conversions, including e-commerce purchases or app downloads. Adjust, AppsFlyer, Branch, Singular and Kochava are the only official MMPs in both Facebook and Apple‘s attribution partner programs.


Multi-touch attribution is the measurement methodology that aims to accurately apportion credit to specific media or marketing tactics that led to a conversion or outcome, such as a sale, as opposed to last-touch attribution standards that reward the final ad or site in the online customer journey.

Privacy & Regulation


Europe‘s General Data Protection Regulation, implemented in 2018, established rigorous privacy standards for companies or marketers that use data to profile or target EU citizens. The GDPR also gives European citizens multiple data rights, including the right to see the data a company has collected about them and the “right to be forgotten,” which requires a business to erase its data or profile of an individual on request.


The California Consumer Privacy Act, introduced in 2018, set new data privacy standards for how businesses and technology companies can collect and use personal information in the state. The CCPA is considered a potential forerunner of a federal privacy law.


The California Privacy Rights Act, passed in 2020 following the implementation of CCPA two years earlier, established the California Privacy Protection Agency. This group has been designed to serve as an independent auditor to enforce privacy laws in California and raise awareness of privacy issues among consumers.

Competition and Markets Authority (CMA)

The British government department tasked with antitrust and anticompetition regulation. For comparison‘s sake, the United Kingdom‘s CMA and ICO are both investigating Google‘s Privacy Sandbox proposals; the CMA is investigating whether Google is leveraging its privacy policies to advantage its own ad business, whereas the ICO looks for potential consumer privacy violations in how the data is used.

Digital Markets Act (DMA)

The European Union presented this potential law in late 2020. The DMA would designate large web companies such as Google, Facebook and Amazon as “gatekeepers,” making them subject to anti-competitive scrutiny. Specifically, these companies would be required to be far more transparent when it comes to sharing data on their advertising businesses and other practices.

Industry Organizations

Interactive Advertising Bureau (IAB)

The IAB is an industry trade group dedicated to online advertising. The IAB and IAB Tech Lab working groups are the main venues for digital media companies, adtech companies and marketers to collaborate on online advertising standards and market research.

Partnership for Responsible Addressable Media (PRAM)

PRAM is an ad industry initiative with a mission to safeguard consumer privacy while protecting key advertising functions like targeted and personalized ad campaigns. It is backed by trade groups such as the Association of National Advertisers (ANA), the Interactive Advertising Bureau (IAB) and the American Association of Advertising Agencies (4A‘s), as well as large advertisers and adtech companies.

World Wide Web Consortium (W3C)

The W3C is the organization that oversees infrastructure-level standards, such as how webpages render and communicate with the browser. The W3C is becoming a more active player in programmatic advertising because browser operators such as Mozilla, Google Chrome, Apple Safari and Microsoft Edge have new infrastructure standards that directly affect web advertising.

Launched in 2017, is a nonprofit, open-source platform designed to make adtech tactics such as header bidding more accessible. In 2021, it was announced that would manage the industry-wide cookie alternative Unified ID 2.0, which was first developed by The Trade Desk.

Media Types

Walled gardens

The internet‘s largest platforms with huge user bases that log in to access their services, generating vast amounts of data that can be used to target and attribute online ad campaigns without cookies. Google, Apple, Amazon and Facebook are the digital advertising industry‘s largest walled gardens. These platforms also can only be accessed by buyers through their own buying tools; they do not give access to any independent platforms.

Mini walled gardens (aka hedged gardens)

A growing number of digital ad platforms maintain exclusive datasets that can be used for ad buying purposes, but unlike Google and Facebook, these companies often do not own and operate complete buying stacks. For example, companies like Target and Walmart let advertisers employ their data on shoppers for ad targeting, but brands can use their own buying tools. Other examples of mini walled gardens might include connected TV platforms such as Vizio‘s or Samsung‘s in-house ad businesses or a digital gaming company that has logged-in users but works with other adtech players to execute campaigns for brands.

Open web

The open web is often a catch-all term for digital media beyond the walled garden platforms, such as Google, Facebook and Amazon. Millions of sites comprise the open web, from independent bloggers and creators to the largest news publishers. These sites use open-source standards to deliver content to consumers without a separate app or company acting as gatekeeper.


Apps are mini programs built and optimized specifically for the design, navigation and functionality of mobile devices. Many phones feature built-in apps for basic functions such as news, weather or mobile payments. Given the increased prominence of mobile computing, tech companies like Google and Facebook, content companies such as CNN and BuzzFeed, as well as other brands typically build app versions of their core products for both Apple‘s iOS operating system as well as Google‘s Android system. A growing number of companies are built with mobile apps as their core product, such as Snap and Uber.

Connected TV (CTV)

Essentially, CTV refers to viewing that occurs via a smart TV over the internet. CTV can include both livestreaming of linear networks as well as on-demand viewing through apps. While ad-free services like Netflix and Amazon Prime tend to dominate CTV viewing, an increasing number of services feature advertising. The ad business is banking on CTV advertising marrying the best of traditional TV — impactful ads that feature sight, sound and motion — with the targeting and tracking power of digital advertising.



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