What is it?
If your hotel uses the Checkin function (Concierge > Check-in form), it gives your guests the option of sending their checkin information to you prior to their arrival:
When a guest fills in this form, the data will be sent to your property in an email.
This page allows you to see all the guests who opted to provide that information:
Clicking the Guest's name opens their profile for that stay, where you can view the information they provided you.