A bookmark is a set of nodes you frequently need to access. Let's say, for example, you have these 4 nodes open in node editors:
(Customer) (Invoice) (Company) (Payment)
and you wish to save that node editor setup for later use (and without having to open all the nodes manually again), then you simply add a new bookmark by giving it a distinctive name and clicking the add button.

You can recall a bookmark by clicking on it and you can delete a bookmark by clicking the trashcan button delete in the bookmarks dialog.

NEW: Deep-Linking to neo4j Browser

When using neo4j Commander inside of neo4j Desktop, a single click opens neo4j Browser and auto-fills it with a query to return the current nodes.