Something placed in a book to guide in finding a particular page or passage; also, a label in a book to designate the owner; a bookplate.
Bookmark are equivalent to Favorites (Internet Explorer a.k.a. IE). Bookmarks server the purpose of stamping a certain web page that you find intriguing and want to save the website URL address.
A placeholder for interesting or frequently used Web sites, so that these sites can be revisited easily without having to remember or retype the Internet address.