Once younger children are finally asleep, this is often the only quiet stretch of the day anyone gets, and it disappears faster than expected. If 10:59 pm is when it has to end, a live countdown gives that stretch an edge rather than letting it drift towards a much later night.
Nothing is downloaded, nothing is registered, and nothing is left on the device afterwards. The whole count runs inside the page you already have open. Closing it costs nothing at all, and opening it again later simply shows the accurate gap to 10:59 pm as it stands at that moment.
Plenty of phones, laptops and dashboards default to a 24-hour display regardless of how people around here actually talk, so 22:59 may well be the figure staring back at you even though 10:59 pm is how the same moment would be said aloud. Neither is more correct than the other.
Common questions
Is it affected by the clocks changing?
Only in the sense that your device is. When the change between GMT and BST happens at the end of March and October, the device adjusts and the countdown follows it without anything to do here.
What is 22:59 in the 12-hour clock?
That is 10:59 pm, or one minutes to eleven at night if you are saying it aloud. From 13:00 onwards, subtracting twelve gives the pm figure — the same moment written three different ways.
Does the number update by itself?
Yes. It recalculates every second from your device's clock, so there is nothing to refresh or restart. Whatever is on screen is the current gap to the target time, not a figure worked out when the page first loaded.
What happens if 10:59 pm has already gone for today?
The count simply carries on towards the next occurrence, which is tomorrow. That rollover happens on its own — the page does not need reloading and there is nothing to reset by hand.