By this stage the kettle has usually been on once already and the radio is halfway through the morning news, which is precisely when nobody is watching the clock. A live count to 10:51 am does that watching for you, updating continuously so the number in front of you is always the current one.
The figure on this page comes from your own device's clock, checked continuously and recalculated every second against 10:51 am. There is nothing to press and nothing to set up first — the count is already running by the time the page has finished loading, and it keeps going while you are looking at it.
Matching what somebody said against what somebody wrote is easier with all three versions to hand: 10:51 am for everyday reading, 10:51 for anything printed in railway style, and nine minutes to eleven in the morning for whatever was actually spoken down the phone. All three describe precisely the same point in the day, and having them side by side saves a good deal of squinting at a timetable.
Common questions
What happens if 10:51 am 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.
Which clock does it use?
Your own. It reads the local time and time zone from the device you are looking at, so the figure reflects where you actually are rather than a fixed zone written into the page.
Will this alert me when the time arrives?
No. It is a live number rather than an alarm — nothing rings, buzzes or notifies you at zero. If you need to be interrupted at 10:51 am, set an alarm as well and treat this page as the running total.
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.