Clickstream data is easy to collect and hard to use. Every modern system can emit page views, taps, API calls, and application events with timestamps and attributes. The trouble starts when analysis or downstream services require a notion of “user.”
In most production systems, identity is incomplete by default. Many events arrive without a logged-in account. Cookies reset. Mobile devices are shared. IP addresses rotate. A single person often appears as several disconnected records, while unrelated users occasionally collide on the same attributes.