Papers, Please – ID in Digital Advertising

Device ID

Click ID and Device ID are of the most indisputably important techniques in the world of digital advertising as it exists today. At first glance, they seem similar – they both ID the user, right? Alas, even among those who have spent a considerable amount of time in the industry, little effort is often put into genuinely understanding the terminology used and less in understanding the technology they describe.

This lack of a truly deep understanding of critical aspects of the industry is something that we will undertake to change. Knowledge might not always be power, but a modicum is needed to successfully navigate such a complicated and rapidly changing landscape as modern digital advertising. 

When it comes to tracking users and conversions reliably, these two technologies, though they be very different in scope, are both of crucial (but not equal) importance. 

Were modern digital advertising a ship, click ID would be its mainsail, device ID its foresail. One of greater importance than the other, but the vessel would find itself in hopeless condition if either were lacking. 


What’s the point of all these IDs? 

Few industries are so concerned with tracking as digital advertising. Everything in this industry is observed, monitored, recorded, analyzed, reviewed, and so forth. There isn’t a single user parameter, a single user behavior, a single obscure aspect of demographic information that wouldn’t be useful to some digital advertiser, somewhere, at some time. 

However, today, there are only two forms of ID to be discussed, and they are almost certainly the most important. 

These are Click ID and Device ID. 

The former is generally utilized in the tracking of clicks, the latter of devices. While many aspects of digital marketing may have a seemingly indecipherable nomenclature, Click ID and Device ID are wonderfully self-explanatory. 

But what are they exactly?

What is Click ID?

Click ID is a unique alphanumeric identifier that is generated when certain links are clicked on. This ID connects the clicker to the click that he made (generally in an anonymous way). 

One of the primary uses for this unique ID is conversion tracking. With a Click ID, one keeps track of where a click came from and who sent it to a given merchant, business, or advertiser. 

The ability to track individual users is extremely useful for deciding who gets paid when a customer then “converts.”

That conversion could be any number of things depending on the product and how payment is set up between a business and an advertiser. 

An advertiser might pay per install, per purchase made on a site, by retention, or by any number of other schemes. One can set the goalposts for “conversion” practically anywhere. 

But no matter where the goalposts for conversion are placed, Click ID is a crucial part of measuring progress towards those goals

But what does that look like in practice? 

Click IDs in the real world

One of the easiest to understand applications of Click ID is affiliate marketing. So let’s look at a simple example of affiliate marketing.

A few days ago, I was looking for a quality air purifier since it’s winter in Estonia (i.e., can’t open the windows without freezing) and the kind couple that lives below smokes like three packs of cigarettes per day. 

This smoke comes right up to the next floor, so now I’m looking for an economical air purifier that can effectively deal with cigarette smoke. 

Apparently, this is an issue that lots of people have because there are thousands upon thousands of lists designed to answer precisely this question. 

Why? Because the people that make these lists can make a ton of money in affiliate marketing if they have good SEO. Every single link on these lists is an affiliate marketing link. 

That is to say, when you click on it, you end up with an absurdly long URL like this:

So let’s break this link down into its principal parts since it contains a lot of information. 

First, there’s the actual URL part that takes the user to his intended destination, but a lot of other data is included in the URL that tells Walmart all about where the click came from and who should get paid if I buy anything. 

There’s the Source ID that gives Walmart the exact website that I was on when I made the click. This information helps Walmart learn about its customers and where people likely to convert are coming from.

There’s also the Walmart Partner code of the site owner, i.e., the individual or company that will be paid for driving my purchase. 

Lastly, there’s the Click ID. Click ID is the unique alphanumeric number generated for this exact click in the process of being redirected to Walmarts site. 

Here’s another example of Click ID in the wild

Beyond simply looking for a new air purifier, I also want to buy a higher quality washing machine. Naturally, such a search begins with typing “best washing machines” into Google – which gives me thousands of imperceptibly different listicles. 

All of which are filled to the gills with affiliate links.

So, finally, I find one that interests me, and I click. And I end up with this link:

Again, after just a glance, we can easily find the Click ID that the system has generated for me. 

There is, of course, other information in the URL such as the campaign ID, referer, location, etc. 

In short

Click ID is a unique alphanumeric code that a tracking system generates when a link is clicked on. Affiliate marketers and digital advertisers make heavy use of Click ID for conversion attribution because it allows a click to be attributed to a host of other information and, more importantly, who drove the conversion.

This tracking setup is known as Server-to-Server or Server-Side tracking. 

Device ID

Device ID has nothing to do with Click ID. There are only two things that lead to them occasionally being lumped together. The first is that they sound similar; the second is that they are both critical elements of modern digital marketing. 

So what is Device ID then? 

Well, it’s a lot simpler than Click ID: Device ID is simply a static code attached to your smartphone or tablet. 

When you first power on your Android or iOS device, a code activates that refers specifically to your device. In a way, it’s like a model number, MAC address, or an IP address. 

It’s a way of identifying your specific device among all the other similar ones out there. 

It’s also an identifier that is easily accessible to app developers and in-app advertisers. And a constant and convenient means of identifying a specific device is a godsend for advertisers. 

So what doe these IDs look like? 


For Google, their Device ID is called “GAID,” or Google Advertiser Identification. 

Every Google Android device has a static GAID that is accessible to developers and in-app advertisers. GAID plays a crucial role in the tracking of clicks and engagement on ads, as well as events that occur in-app later on.

This is important because a lot of Cost Per Action payment regimens require specific actions to be performed in-app after install before the conversion is counted. 

Even with Cost per Install campaigns, it is generally only considered a CPI conversion after the installed app is opened for the first time.


For Device ID, Apple uses a code called Identifier for Advertisers or IDFA. Every iOS device, be it an iPhone, iPad, or iPod, has an IDFA. This IDFA is used almost exactly the same way as GAID is used in Android devices.

It allows for the tracking of user behavior, in-app events, and in-app advertising events. 

Passing Device ID

Many advertisers want Ad Networks to “pass” Device ID to them. Passing is simply the process of handing data to another party through the Server-Side tracking URL system that has become the industry standard. 

Advertisers often request this information so for a few reasons. 

For one thing, it allows them to be sure that their offer is being served in in-app traffic only. This is because the other kind of mobile traffic, mobile browser traffic, cannot pass Device ID back. 

Device ID is only accessible in-app. So if Device ID is passed back to an advertiser with Click ID, then that goes a long way to proving that the traffic and clicks in all in-app. This limited accessibility is important because in-app traffic often has a much higher click-through rate than mobile web traffic, so advertisers want to make sure that that is where their traffic is originating. 

Further, gathering Device IDs allows for a deeper understanding of customers, and it can be an essential tool in the combating of mobile advertising fraud (such as device farms, emulators, etc.).

Device ID Privacy

Privacy is one of the most critical issues facing digital advertising today. The industry is built on developing a better understanding of clients and what kind of ads would be more likely to lead them to make a purchase or convert, as it were. 

This means that one of the most critical aspects of digital marketing is tracking users, understanding them, and building a profile on them. 

Some users, however, often don’t like that they’re being tracked. They don’t like that some faceless company is building a much more profound profile on them (even it’s smaller than the profile that they willingly give to Facebook and Google). 

In order to address this concern, mobile operating system developers (that is to say, Google and Apple), give the users the opportunity to reset his Device ID if he so chooses. 

Naturally, this throws a relatively large wrench in the very delicate tracking process, rendering a lot of information completely useless.

Click ID Privacy

Privacy is much less of a concern with Click ID since it is generated on the spot and only lasts for one click – whereas Device ID tends to last for the lifetime of a device. 

Click ID in Server-2-Server

Click ID is generated when a click is made on the “supply” end, that is to say, on the site where the ad has been placed. That click ID is generated by their tracking system and then passed to the DSP or Demand-Side Platform. From the DSP, it is then passed on to the individual or company that is paying for the ad. This individual could be an agency or the company itself whose product is being advertised. 

If the user ends up converting, then this Click ID is then reported back to the publisher server. This process of returning a Click ID that has become a conversion is known as “postback.”

Conclusion and Review

While Click ID and Device ID have little in common outside of a similar name, they are both of incredible importance in the modern digital advertising industry. 

Click ID itself is essential to practically all kinds of non-cookie-based conversion tracking in 2019. In a world dominated by Server-to-Server conversion tracking, Click ID is the essential identifier that allows conversions to be attributed. 

The omnipresence of Device ID in the digital advertising market goes to show how much mobile is dominating the arena nowadays. The majority of digital ad spend in developed countries is targeting mobile users; in developing countries, mobile is practically the only game in town. 

Device ID is a godsend for advertisers as it is static for each device, accessible by applications and in-app advertisements, and – most importantly – it is very rarely reset. All these factors combine to allow for excellent tracking of conversions, in-app events, and user behavior. 

These two IDs, while functionally very different, form two of the key pillars in the massive digital advertising edifice. And understanding their importance and their place in the edifice is key to being able to thrive in the market.  

Mobinner is a High-Performance Demand-Side Platform. Since 2017, we’ve been helping our clients build brandsdrive conversions, and acquire users. See what Mobinner can do for you!

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