To give better flexibility in their schedules your users can take Half Days Off or Half Days AFK. Both work very similarly, but it’s worth noting how these are different from full Days Off and AFK.
How are Half Days shown?
In Planner and My Schedule the Day Details widget will indicate if a day is Half Off or Half AFK. They’ll have the same background color as Full Days Off (purple) or Full Days AFK (blue). But since you’re still working part of the day, they also show your availability and task requirements like regular working days.

How do Half Days affect my schedule?
Since you still set available time on Half Days, you don’t need to specify which half of the day you’re taking off. This gives you a lot of flexibility, for example you can take time off in the middle of your workday by setting a Half Day AFK with availability just in the early morning and late afternoon.
Because you work less on a Half Day, it will reduce your available and schedulable hours requirements. Both will be reduced to 4 hours (or if it’s already set lower than 4 it will stay the same). So if you normally work 8 hours in a day, it will be reduced to 4 hours. If you normally work 6 hours, it will also be reduced to 4 hours.