Bookmarks are used in SSMS to have SSMS remember selected line positions, and to quickly move between the bookmarks. All of the Bookmark functionality is in the Bookmarks submenu, off of the Edit menu:
A bookmark is toggled with the Ctrl+K, Ctrl+K keyboard shortcut, or by using the menu option shown. When the bookmark is set, there will be an icon off to the left of the line:
When you have multiple bookmarks set, you can move to the next one with the Ctrl+K, Ctrl+N keyboard shortcut, and you can move to the previous bookmarks with the Ctrl+K, Ctrl+P keyboard shortcut. All of the bookmarks can be removed with the Ctrl+K, Ctrl+L keyboard shortcut.
This post is for day twenty-four of my month-long blog series “A Month of SSMS Tips”. I have a landing page for the series at bit.ly/MonthOfSSMS. Please visit this page for an easy place to quickly view all of the other tips in this series.