Visual QuickProject Guide: Organizing and Editing Your Photos with Picasa

Work with Labels

Just as collections are used to organize folders with common content, you can create labels (special Picasa-only folders) to group similar files—regardless of their location on disk. Although a folder can be in only one collection, an image file can be in as many label folders as you want. Adding a picture to a label doesn't move it from its folder on your hard disk. Files in a label are simply shortcuts to the originals rather than the actual files. As such, removing a file from a label doesn't delete it.

Create labels. You can create as many labels as you like. After creating the first label, Picasa creates a Labels collection in which all labels are stored.

Select the images for this label, adding them to the Picture Tray. ...