The Bookworm
uses Bookmarks
to mark Pages
in a Book,

The Firefox
uses Bookmarks
to mark Pages
on the Net.

The Dog-Ear
is a Bookmark
that leaves a Mark
on the book Page,

The Facebook
can share Bookmarks
to the Pages
that you set.

The Silverfish
makes Tooth-Marks
on the Page-Ends
of a Book,

The Myself,
I've not figured out
what a Bookmark
is, yet.