Let's say you run a rental business with lots of logistical considerations.
You take bookings and you move inventory around from town to town, city to city.
You need to make sure you don't make any silly mistakes in your scheduling like having a bike in New York one day, and 100 miles away the next day.
For this reason we developed 'availability shoulders' as an option, so that when you check your availability you can see what is going on, with that bike, the day before and the day after:
the light blue are the 'booking shoulders' either side of the dates being booked so you don't make any silly mistakes:
please note that if you have booking shoulders enabled it will also show up when you use 'show planner'
But please beware, if you have online booking it doesn't stop someone making a booking for the 'blue' areas of your calendar, so you need to be careful. For that feature you would need to wait until booking buffers have been enabled, but it is a complex feature request.
If you are interested in this feature please raise a ticket with support.