Conversion
Event tracking
Also called interaction tracking.
Event tracking is the practice of sending named interactions into the same stream as pageviews. It extends measurement beyond loads.
How it is measured
A plan names each event, chooses where in code it fires, and decides what data it carries. A good plan also says who reads it.
Tarsier makes the minimum viable plan easy: one call per event, a name and optional short data.
Worked example
A bike-rental site plans six events: search_started, bike_selected, checkout_started, paid, pickup_confirmed and review_left. After a month the team sees 1,200 search_started and 190 paid. The biggest gap is between bike_selected and checkout_started.
They find the price only appears at checkout and show it on the bike card. The gap closes by a third.
How it differs
Event tracking is the practice. An event is the record. Custom event and automated event are two ways to create one. Conversion is the event you care about most.
Common errors
Tracking without a question. Inconsistent names. Firing before the action succeeds. No owner for the plan. Not testing after releases.
In practice
Write a one-page plan with six events at most. Review it after a month and delete anything nobody read.