Set up a search here the way you would normally, typing in the Spotlight field and clicking on the plus-sign (+) buttons to add criteria (for example, created or modified dates). The window that opens looks like a standard Finder search window, but its title is New Smart Folder. To create a smart folder in the Finder, select File -> New Smart Folder (or press Command-Option-N). Smart folders can save you time when you would otherwise need to rebuild a search from scratch, helping you find, track, and organize files and folders.
These dynamic folders-which don’t actually hold anything, but merely list items stored elsewhere-continually update to display the items on your computer that meet your search criteria.
Want to keep track of all documents you have greater than 500MB in size? All your PDFs? All your OpenType fonts? Pictures taken with your Canon PowerShot within the last two weeks that have less than a specified focal length and greater than a specified exposure time? If you can set up a search for something in the Finder, you can make a smart folder for it too.
