
They can show you most visited or recently added bookmarks, moreover you can add bookmarks that monitor specific websites, your own browsing habits, and more.
How to make smart bookmarks:
Create a new bookmark the way you normally would in Firefox, then modify the "Location" field using Mozilla's parameters list:
10 Most Visited Sites:
place:queryType=0&sort=8&maxResults=10
10 Most Recent Bookmarks:
place:queryType=1&sort=12&maxResults=10
15 Most Visited Bookmarks:
place:queryType=1&sort=8&maxResults=15
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