Traffic
Active users
Also called current users.
Active users is the count of visitor identifiers that sent at least one hit inside a short live window, usually the last five or thirty minutes. It answers who is on the site right now, not who came today.
How it is measured
Take every hit received in the trailing window and count the distinct visitor identifiers. The unit is a person-ish identifier, not a hit, and the window slides forward every few seconds. A tab left open on a page that stops sending heartbeats drops out once the window passes.
Tarsier counts a cookieless visitor as active while its script is still sending a presence signal, with no cookie to say who it was yesterday. The live board and the globe both read from that same window, so the two numbers should agree to within one refresh.
Worked example
A wine shop sends a newsletter at 10:00 sharp. At 10:03 the live panel shows 212 active users, at 10:20 it shows 64, and by 11:00 it is back to 9. Nobody was lost. The window just stopped counting people who read the email and closed the tab.
The owner screenshots the 10:03 figure for a partner and calls it daily traffic. Daily traffic that morning was 1,380 identifiers. The screenshot described three minutes.
How it differs
Active users is a rolling snapshot of presence. Real-time analytics is the reporting style that makes such a snapshot possible. Daily active users uses a calendar day, so one person who visits at 09:00 and 21:00 counts once there and may count in two different live windows.
Common errors
Reading the live figure as a day total. Comparing a thirty-minute window to a five-minute window from another tool. Forgetting that background tabs may stop sending signals. Treating a spike during a launch as stable demand. Counting yourself and your team.
In practice
Pick one window length, write it on the dashboard note, and use the live view for launches, outages and email sends. Exclude your office IP before you trust a quiet Tuesday. For anything you report upward, switch to a calendar-day or weekly count.