The book marker. It is as the name calls it, and it is really helpful. I never knew the importance till when I had one in my Bible, it made the identification of the verses easy to locate. The bookmark can also be used to save a particular website you visit often, it makes it like a shortcut. The concept is quite nice.
The participation link:
@mariannewest/day-1867-5-minute-freewrite-friday-prompt-bookmark