Because of the nature of the internet, a typical analytics implementation can only track one top-level domain at a time. Largely, this is due to a number of fail-safes built into the framework of the internet, as well as Google’s own fail-safes, and is meant to prevent code on your domain from interfering with the functioning of another person’s or company’s’ domain.
However, with cross-domain tracking and some slight modifications to the way your properties interact, it’s possible to count visitors across all domains from a single dashboard, as well as preserve continuity in visitors who might hop from domain to domain.
Who should use cross-domain tracking?
Companies With Multiple Branded Pages: A strong candidate for CDT would be a company that operated multiple brands but wanted a unified analytics reporting solution. Tracking visits to multiple brands in one place can reap large savings for some organizations simply by combining analytics duties across brands and eliminating redundancies. More interestingly, though, companies can more easily and effectively compare domain performance and the impact of things like pricing, design, and navigation. These kinds of insights are incredibly valuable to companies.
With e-commerce sales set to grow 10% annually over the next 5 years, the ability to use cross-domain information to raise conversions by even a few percentage points can result in large dividends. Just the ability to quickly and easily compare inbound organic keywords to prevent brands from unintentionally competing and stealing traffic from each other, or vice versa to make sure multiple brands are able to crowd competitors out of search results, can be worth millions to a company.
Third-Party Shopping Carts: Another commonly-presented example are e-commerce sites that use third-party shopping carts. Without a good cross domain tracking implementation, there would be no unification of data and visits to the cart would be counted as entirely separate from visits to the store itself.
Information collected in the shopping cart domain, for instance, would not contain the keywords and traffic sources for visitors who completed a transaction, but would instead be reported as being referral traffic from your store page. Likewise, it would be difficult or impossible to track variables like time spent on site, or which sections of your website led to higher conversions and goal completions.
Separating Site Sections: Another incredibly powerful, but underutilized, use for CDT is the ability to create sub-sections, or zones, on your website that can be tracked as separate entities from one report. A great example of this is an e-commerce fashion site with multiple clothing lines. By treating each catalog as a separate unit, they can more effectively see how users are interacting with their products, and by using CDT, they can do it for every clothing line from one place.
Whichever case fits your situation, the more granularly you can track customer movement across your various domains, the more you can learn about their behaviors, their motivation, and the opportunities they present for your business to grow.