What Is an Availability Window?
TL;DR
An availability window is the range of hours on each day that a scheduling tool is allowed to offer, such as Tuesday to Thursday between 10:00 and 16:00. Real availability is that window minus whatever the connected calendar already holds, so the window sets the outer bound rather than the slots themselves.
How does an availability window differ from free time?
The window is a policy and free time is a fact. A window of Tuesday to Thursday, 10:00 to 16:00, states when you are willing to be booked, then the connected calendar removes whatever is already scheduled inside it, and what survives is offered.
That is why a window alone never causes a double-booking and a window without a live calendar connection eventually always does. The policy is static and the calendar is not.
What else narrows the slots that get offered?
Four rules sit on top of the window: buffer padding around existing meetings, a minimum notice period before the earliest bookable slot, a cap on bookings per day, and a limit on how far ahead the link may reach.
Slot granularity is the quiet one. Offering times on the half hour rather than every 15 minutes shows fewer options and produces cleaner days, at the cost of the bookings that would only have fitted in the gaps.
Frequently asked questions
The window is stored in the time zone of the person being booked and rendered in the time zone of the visitor. A window of 10:00 to 16:00 in Berlin shows as an early morning to somebody in California, which is what makes a second window worth adding for a distant region.