Picasa is a desktop photo library for finding, grouping, editing, and exporting pictures already stored on a computer. It builds a visual catalogue across selected folders, but it does not place every image into one new master folder. The distinction between folders and albums controls what happens to the original files: a folder mirrors a real disk location, while an album is a Picasa-only collection that can point to photographs kept in several places.
Folders affect disk
The Folder Manager determines which locations the catalogue watches. Removing a folder from the library can hide it from the catalogue without deleting its pictures. Moving a photograph between watched folders changes its location on the computer, however. Deleting from a folder can also remove the actual file. This behavior differs from removing the same photograph from an album, which changes only the catalogue grouping.
Albums let one photograph appear in several projects without creating several file copies. Picasa can also group similar faces under People and create an album for each named person. Face matches still need human checking; a wrong name can spread across a group when the user labels several suggested faces at once.
Edit without replacement
The editor handles common corrections inside the library. Crop cuts away part of the frame, Straighten fixes a tilted horizon, and Redeye targets flash reflections. Retouch, Fill Light, colour controls, text, rotation, and filters remain available beside the original preview. Side-by-side views can compare two photographs or show the edited image next to its starting state.
The editor preserves an original, but the Save command changes the folder arrangement. Picasa writes a new edited version and moves the starting file into a hidden subfolder named .picasaoriginals. A person who opens the folder in File Explorer may therefore think the original disappeared. Save a Copy follows another rule: it keeps the source in place and adds -1 to the copied filename. Save As lets the user choose a different name and location.
Export makes JPEGs
Export creates copies for email, another device, or a separate archive. The export window can resize photographs and add a text watermark. Picasa writes edited photographs as JPEG files, so exporting is not a neutral container for every source format. A camera original in another format remains important when later work needs the data that a JPEG copy no longer carries.
Duplicate detection can skip a photograph that Picasa already knows during import. A red X identifies a detected duplicate. This check depends on the catalogue and selected folders, so repeated copies that already sit in different watched directories may still require Folder Manager, Hide, or a manual deletion decision.
Offline after retirement
Google retired Picasa and stopped distributing updates. An existing installation can still organise and edit local photographs without an online account, but the old web workflow no longer functions as a maintained service. Installing an archived copy on a new computer also carries more risk than installing a currently maintained editor because no future security or compatibility fixes will arrive.
Photographs and videos that once lived in Picasa Web Albums moved into Google Photos. Picasa-specific comments, tags, and +1 marks did not make that move. The desktop face groups and albums should therefore be treated as local catalogue data rather than the only record of organisation. Keeping the picture folders and a separate backup matters more than preserving one Picasa database alone.
