What is Cross Device Advertising?

Cross device targeting enables the advertisers to target their audience across multiple devices such as Mobile, Tablet, Desktop and Laptop. For example: If a user has visited the Amazon website to purchase a Smartphone via desktop, then with the help of cross device targeting, it is possible to retarget that user on multiple devices such as Tablet, Mobile, Laptop etc,.

Cross Device Advertising

You might be thinking that when we are targeting the ads based on cookies on the desktop, we can also do that same thing on mobile based on the cookie then you're wrong, it is difficult to track the user identity using cookies because of the following challenges:

What are the challenges of Cross device targeting?

• Whenever the mobile browser is closed, the browser will reset the cookies
• Few mobile browsers doesn't allow the 3rd party cookies by default such as safari, however they do allow the 1st party cookie. Let's understand the what is 1st party cookie and 3rd party cookie. 
• 1st party cookies are used by the website owners(the website which you have visited for example, you have visited Amazon website and Amazon.com has placed cookies and the cookie information is used by the Amazon.com for enhanced user experience). 
• 3rd Party cookies are used by the website vendors(the visited website may also website vendors cookies, for example you have visited foxsports.com and advertisting.com website might use cookies of foxsports.com for targeting the relevant ads).
• Mobile Apps doesn't share information with Mobile Apps/browsers as they mobile uses Appview concepts formally called sandbox where the information is shared within the mobile  app, Please refer to the below screenshot by IAB

Availability of cookies on apps and browser, for android and ios

Keeping the goal of identifying or matching the right users with existing available data across multiple devices is broadly divided into two types:

• Deterministic data in Cross Device Advertising
• Probabilistic data in Cross Device Advertising

Deterministic Data in Cross Device Advertising

Deterministic Data is based on the user login(Personal Identifiable information) across the multiples devices and it is considered as the accurate data because when the user logged into mobile app or browser(we can track device ID, user login), and the same user is logged into other devices such as desktop, tablet browser then we can determine that the user is a unique using multiple devices. 

Therefore we can accurately target the user who is connected multiple devices based on the user-login. However, this is possible when you have large database such as Facebook, Google, Twitter, LinkedIn etc,. 

Deterministic Data

Probabilistic Data in Cross Device Advertising

On the other side of coin, Probabilistic Data is based on non user login(non Personal Identifiable information) which means we infer the data using different attributes such as IP address, browsing data, device information and prospect the user based on the existing data by creating data points using machine learning algorithms. Since, we are inferring the data based on various attributes may change for example, Operating System updates, it is not accurate as Deterministic Data. 

Probabilistic Data

With the help deterministic data and probabilistic data, the ad tech companies target the right users across the multiple devices effectively with cross device advertising or cross device targeting

Advantages of Cross Device Advertising

• It solves cross channel tracking issues meaning, before the invent of cross device tracking, ad tech companies used track as single conversion as two different conversions, one for mobile and one for desktop. It eliminates the de-duped conversions
• Cross device helps understand and analyze customer behaviors 
• It helps to serve impressions effectively and utilize the multi-channel inventory
• Marketers can spend effectively for each impression served to the visitors
• Marketers can able to set up the sequential messages

Disadvantages of Cross Device Advertising

• Sometimes, in a family, people tend to share the devices and ads may be served to other members of family. For example, in a family, if X is logged into the tablet browser and Y is browsing the web using X logins on tablet, then the ads will be served to the X across multiple devices. This is a rare scenario in cross device advertising
• To identify the user accurately, you need to huge amount of data.

It is important to refrain the number of times an ad is shown to the user because the user fed up viewing the ads across all devices and also save the impressions from being wasted when Cross device targeting is implemented. As of now, there are many ad tech companies which offers cross device targeting such as AdRoll, Drawbridge Criteo, Facebook, etc,.