When making a Reservation or Check-out, you might want your users to fill in some extra information. Say, for example, what project or class it will be used for. Or perhaps the project name and ID would be nice to know?
By setting up required fields, your users won't be able to complete a booking before filling in the necessary information.
Creating a required custom field
Go to your Settings in the bottom left corner of your screen
Click Fields
Next, select Reservations or Check-outs
Click Add field
Enter a field name and select the right kind
Choose to make it required
Making an existing field required
Go to your Settings in the bottom left corner of your screen
Click Fields
Next, select Reservations or Check-outs
Hover over the field you want to make required
Click Actions and click Edit
Choose to make it required
Click Update
How the required fields work
Once you have created a required field for either Reservations and/or Check-outs, your users won't be able to finalize the booking without filling in the required field: