Engineering & UX Glossary
Master the terminology of modern session replay, observability, and user behaviour analysis — every term defined the way engineers actually use it.
Session Replay
A technology that captures user interactions on a website or application and reconstructs them exactly as they happened.
DOM Serialization
The process of converting the live state of a web page's Document Object Model into a persistent data format (like JSON) that can be stored and later reconstructed.
MutationObserver
A built-in Web API that provides the ability to watch for changes being made to the DOM tree.
Rage Click
A behavioural signal: the same user clicks the same target three or more times within a short window, indicating that whatever they expected to happen did not.
Dead Click
A click on an element where nothing visibly changes — no DOM mutation, no network request, no navigation — within a short window after the click.
User Friction
The cumulative effort, hesitation, and recovery a user expends to complete an intended task — usually proxied by behavioural signals like rage clicks, dead clicks, scroll U-turns, form abandonment, and dwell time on a stuck state.
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