A user journey is basically a chronological sequence of touchpoints. A user has visited your page in a certain time range (lookback window)  and may or may not converted on a special event you defined as success.

As this definition reads a lot like a technical description we now want to give you some more details and depth about customer journeys, which will help you to get the concept. 

First of all - a user in the world wide web is something completely different as we would assume from what we know from the 'real world'. We would assume a user is a physical person, always the same. But as the digital world is....well digital! we can not trust our real world assumptions. A user in the internet is pretty much a browser or at least a device, determined and recognized by cookies which were set in your browsers. Thus one 'real world user' is probably recognized as several 'online users' because it uses more than one device to stroll around the internet and your website. 

As you may see by now - the user concept is a little bit fuzzy. Adtriba (and everyone out there in the web) tries to find mechanisms to actually match all the different devices and browsers back to one single 'real world user'. And good news! We can do that! We only need a userspecific identifier which is transmitted once a user is identified on your website. Normally this is either your unique customer ID or the hashed emailadress of the user. Once the user is successfully identified on all its devices, we can match all his cookies into one 'real world user'. This concept is called probabilistic cross-device matching.

But why is it important anyways to identify a user across all its devices? As stated above a user journey includes all touchpoints - and how can we track all of his touchpoints if we don't know all of its devices?