Brands spent 2021 rushing to build first-party relationships with consumers and navigating new forms of ad IDs in the wake of data lockdowns and yet another turn of events in the demise of third-party cookies. 

In April, Apple rolled out its App Tracking Transparency framework, which created new hurdles for brands to target ads and measure campaigns. The new framework required apps to ask the permission of every user to track their behavior. 

This led brands to find new ways to connect directly with consumers, which became a crucial step to continue personalized marketing under the latest data-sharing restrictions. 

At the same time, Google postponed the demise of third-party cookies, a linchpin of the ad industry used to serve targeted ads. Google's post-cookie experimentation on its Chrome web browser had raised questions about whether the tech giant could kill cookies without also stifling competition from ad tech rivals that relied on them. 

The industry is still preparing for when Google shuts off third-party cookies, even though that isn't expected to happen until 2023 (two years later than planned). New cookie alternatives have cropped up, including ad IDs from most of the major ad tech companies. There was also an influx in new media networks from the largest retailers, which allow brands to tap into their trove of sophisticated consumer data sets.

Here is a look back on the biggest headlines around the cookie and data trends of 2021.

Behind the rankings: Ad Age World's Largest Advertisers 2021

Apple iOS 14.5 looms

The biggest shift in ad tech came from Apple as it finally implemented some of its toughest restrictions on data-sharing on iPhones. In April, Apple’s next-generation iOS 14.5 software came out, altering how all apps access consumer data from users on iPhones.

All of the apps in Apple’s App Store, including Facebook, Snapchat, TikTok and YouTube, had to show a tracking consent form to get users’ permission to collect their data.

After the launch of iOS 14.5, reports showed that most consumers opted out of tracking. Estimates varied, but Flurry Analytics, a Yahoo-owned analytics firm, found that as few as 5% of U.S. users opted into tracking. In May, an Ad Age-Harris Poll survey found more consumers might be amenable to allow tracking from some of their favorite apps.

Google’s cookie reprieve

In another timeline, digital advertisers would be counting down the days until Google shuts off third-party cookies on Chrome, which it was set to do by the end of the year. However, in June, Google made a major announcement that it would stall the death of third-party cookies until the end of 2023.

Google's new timeline was met with mixed feelings in the industry: Some brands were eager to leave cookies behind, while others welcomed more time to work on new alternatives. Google is still experimenting with cookie alternatives in its Privacy Sandbox, but will take longer than expected.

Crisis of conversions

Following Apple’s changes, advertisers reported struggles tracking sales on Facebook ad campaigns. Brands lost the ability to see when an ad on one app led to a sale on another, which is known as a “conversion.”

In September, Facebook told marketers that it found a bug in its ad platform, which was under-reporting conversions by about 15% on Apple devices.

In October, Facebook said that Apple’s privacy policies hurt its potential to make even more money from ads in the third quarter. Snapchat also noted challenges adjusting to Apple, and Zynga reported that Apple’s changes were making it more difficult for the gaming company to conduct its marketing on mobile devices.

See Ad Age's 2021 Marketers of the Year here.

Retail media grows

Large retailers like Walmart, Target, CVS, Best Buy and more have been trying to grow digital ad networks, blending shopper data and ads. That trend accelerated in 2021, with even grocery chain Albertsons joining the fray.

Walmart advanced its ad business by launching its demand side platform, which it built with The Trade Desk. In October, Kroger unveiled a private programmatic ad marketplace with Publicis and Nestlé as early advertising partners. Publicis Groupe also bought CitrusAd, a retail media ad tech company. And online shopping companies like DoorDash and Instacart built up their ad teams.

CTV streams ads

Connected TV is becoming more sophisticated thanks to an influx in data coursing through the ecosystem and more money from brands. This year, Disney and NBCUniversal were examples of top media companies that capitalized on the surge in interest in CTV. After the upfront season, when brands cut ad deals with publishers, Disney said 40% of the commitments went to streaming and digital. That was a double-digit increase, Ad Age reported. NBC also said it secured $500 million in upfront commitments for its streaming service Peacock. 

Also, top ad tech companies like The Trade Desk reported significant increases in ad revenue from connected TV. And Innovid, a video ad tech firm, went public on the New York Stock Exchange.

It wasn’t all rosy, though, as top ad fraud detection companies like WhiteOps, DoubleVerify and Pixalate all uncovered cases of ad fraud in CTV.

Zero- and first-party data dots

Brands created more direct relationships with consumers, which was a direct result of cookie changes and data-sharing restrictions. The more brands obtain consent from visitors to their websites, the more they can compile profiles to target ads to those customers.

In May, Ad Age reported on marketers moving beyond the cookie, with Procter & Gamble, Unilever and L’Oreal each amassing data on more than a billion consumers.

Zero-party data also became a hot term in the industry. This is when consumers' interests are compiled by asking them directly through online surveys, loyalty programs and other incentives.

One company, DataLucent, even introduced a new program that encouraged consumers to download all their data from Facebook, Google, LinkedIn and Twitter to share directly with brands, in exchange for perks.

Apple’s ad ambitions

In September, Apple again tweaked how data gets shared on its devices with the iOS 15 software update. Apple also started building its own ad products that allowed apps to promote their services in its App Store.

The ad industry started speculating more seriously about how Apple could attempt to challenge Facebook through its ad network, beyond just app ads in search results. According an Evercore forecast, Apple could become a $20 billion ad business in no time, if it wanted to.

Ad IDs everywhere

Cookie replacements sprung up from companies like Yahoo, The Trade Desk, Lotame, Merkle, Epsilon, Kinesso, LiveRamp, Neustar and more. These new identifiers can be tied to consumer profiles used for targeting.

Brands have been experimenting more with these IDs in order to prepare for the post-cookie world. For instance, Doc Martens worked with Lotame’s Panorama ID to target audiences through Digo, a Spanish-language publisher. The brand said the ID helped lower the cost of the ads and increased how often consumers clicked on the ads.

The ID space was dealt a setback when Google postponed its cookie expiration date, making the transition to IDs less urgent. But heading into 2022 the clock is still ticking.