Heartbeat Ping

A heartbeat ping is a small request the tracking script sends at regular intervals to signal that the page is still open and the visitor still active.

It exists because the browser fires no reliable event for a visitor leaving, so without it the duration of the last page of every session cannot be computed and that session registers as zero. Each ping usually carries the session identifier and an active or idle flag, and the server treats the final ping as the end of presence. It has two costs that should be accepted deliberately: extra request volume, which counts directly against event quotas, and accuracy bounded by the interval, since a thirty-second cadence leaves up to half a minute of error. Browsers also throttle background tabs, so pings from a hidden tab are normally suspended to avoid manufacturing time that was never spent.