Glossary

Active Library The active library (referred to as “last opened” in some places) is the library that was most recently opened in the Photos app. In PowerPhotos, the active library is designated with a green checkmark next to it in the library list. If you open Photos directly via the Finder or Dock, the active library is the one you will see displayed there. You can change the active library either by clicking the checkmark next to it in the library list, or by double clicking the library in PowerPhotos or the Finder to open it in Photos.

Album To further organize your photos, you can create any number of albums in a Photos library, and add any number of photos to each album. Adding a photo to an album does not create a copy of the photo, so multiple albums can reference the same photo without taking up more disk space. Removing a photo from an album only removes it from that album, so that photo will remain in the library, as well as any other albums it belongs to. Similarly, deleting an album does not delete the photos it contains from the library.

Consolidate If you have imported some photos into your library as referenced photos, Photos provides a “Consolidate“ command in its File menu which will copy those photos from the folder they're located it into the library itself, converting them from referenced to managed photos. You may want to consolidate referenced photos if you plan on copying the library to another hard drive, since doing so will often break any references to external folders.

Convert If you have an old iPhoto or Aperture library that is no longer supported by your Mac, you can use PowerPhotos to convert the library to a Photos library. This replaces the migration feature that used to be available in older versions of the Photos app.

Duplicate Photo The term “duplicate photo“ is actually surprisingly hard to define, since different people have different concepts on whether they consider two photos to be duplicates. Photos that are 100% identical byte for byte are obviously duplicates, but many people also don't want to have multiple copies of what is essentially the same photo even if they're different in some ways, such as one being in a different format, a different size, or having different metadata.

PowerPhotos uses a visual duplicate detection engine that tries to match up photos that derive from the same original photo. It also provides additional comparison options to further narrow down its matches for people who want more precision in what they consider identical, e.g. requiring the photos' filenames or dates to match.

When PowerPhotos completes its search, it refers to all the photos it has found as “duplicates” which are displayed in a number of “duplicate groups”. Each duplicate group will have one photo marked as a “keeper”, with the rest of them marked to be “trashed“.

Event Events were a feature that was implemented by iPhoto, but no longer exists in the newer Photos app. Whenever you imported a batch of photos, they would be put into one or more events, which were an alternate way to organize photos in addition to albums. When you migrate a library from iPhoto to Photos, Photos will convert the events from the iPhoto library into equivalent albums, and store those albums inside a folder named “iPhoto Events” in your library. No new albums get added to this folder as you import new photos using the Photos app though. If you never used events or don't need them any more, you can safely delete the “iPhoto Events” folder from your library.

Export Exporting refers to copying photos from a Photos library to a plain folder outside of Photos. Photos has a built-in export command, but PowerPhotos provide one of its own that offers several additional options above what Photos offers.

Folder A folder, in the context of Photos, refers to a folder created in the album list of your library that you can use to organize your albums into a hierarchy. This is the same concept as a folder in the Finder, but used to group albums instead of files, and it only appears when viewing your Photos library.

iCloud Photos iCloud Photos is a service provide by Apple that will sync your Photos library across multiple devices, including Macs, iPhones, and iPads. On your Mac, only your system library can sync with iCloud Photos.

iCloud Shared Library iCloud Shared Library is a feature Apple introduced in macOS Ventura which lets you share part or all of your library with other people using iCloud Photos. Read here for more information on how PowerPhotos interacts with iCloud Shared Library.

Import Importing refers to adding new photos to a library from outside Photos, either by dragging them in from the Finder, or plugging in an iPhone or other digital camera. You can also import directly into a particular library by dragging photos into a library in PowerPhotos. Importing this way, PowerPhotos can also weed out duplicates in the process.

Incomplete item Some photos or videos in your library can have multiple pieces of data behind the scenes, e.g. an edited copy of a photo or a video associated with a Live Photo. If one of these pieces of data is not present on disk, PowerPhotos calls that an **incomplete item** and performs special handling for it. Read here for more information on how PowerPhotos handles incomplete items.

Keeper After finishing a duplicate search, PowerPhotos displays all the duplicates it has found in a number of duplicate groups. Each group of duplicates has one photo marked as the “keeper”, with the rest marked as to be “trashed”. You can use duplicate rules and manual changes to adjust which photos you want to be marked as the keepers.

Hidden Photos supports “hiding“ photos, by using the Image > Hide Photo menu item in the Photos app. Hidden photos are not displayed when browsing through your library, in either Photos or PowerPhotos, nor are they shown in albums. You can view your hidden photos by selecting View > Show Hidden Photo Album in the Photos app, then selecting the “Hidden” album in the album list. You can then unhide photos by selecting them and using the Image > Unhide Photo menu item. PowerPhotos cannot see or work with hidden photos, so any such photos will not be included when copying albums or merging libraries. If you want them included in your copying operations, you must first unhide them using the Photos app.

Library A Photos library contains a collection of photos and their associated metadata, along with any albums and projects that you've created that use those photos. By default you only have a single library, which PowerPhotos calls the “Default Library”, and that is the library you see when you open the Photos app. PowerPhotos lets you create multiple libraries and switch between them in the Photos app.

A library is a self-contained unit, so making changes in one library does not affect any other libraries. Each library can be seen as a single item in the Finder, and all the photos and other data for the library are stored inside there, so you can easily copy a library from one place to another either using the Finder, or the “Duplicate Library” menu item in PowerPhotos.

Library Group Library groups are a feature provide by PowerPhotos to help further organize your libraries in the PowerPhotos library list. Library groups only appear in PowerPhotos, and moving libraries between groups in PowerPhotos has no effect on where they reside on disk.

Merging Merging libraries is a feature provide by PowerPhotos that lets you combine the contents of multiple libraries into one. During a merge, the contents of one or more existing libraries will be copied into another library, including all photos and albums, with duplicate photos being skipped. Not to be confused with Migrating.

Migrating Migrating is the process of taking an old iPhoto or Aperture library and converting it into an equivalent Photos library containing the same photos and albums as the library. As of macOS 13.0 “Ventura” and later, Photos no longer supports migrating iPhoto libraries, but you can instead use PowerPhotos to convert your iPhoto/Aperture libraries to Photos.

Missing item If a photo or video listed in your library is not present on disk, then PowerPhotos calls that a **missing item** and performs special handling for it.. Read here for more information on how PowerPhotos handles missing items.

Optimize Storage When you have iCloud Photos enabled, you can choose the “Optimize Storage” option in the Photos settings window. With this setting enabled, Photos will not download the full size original photos to your local hard drive right away. You can still browse through your entire library, and Photos will automatically download photos on demand as needed when you view or edit them. This option only applies to your system library, and only when iCloud Photos is enabled.

PowerPhotos can work fully with the Optimize Storage option, and will also download photos as necessary when viewing or copying them. Special care is needed, however, when making a copy or backup of the entire library. Read more about this in the “Backing up your Photos Libraries” section of the PowerPhotos manual.

Partial copy If PowerPhotos encounters incomplete items when performing a copy or merge, you can choose to have PowerPhotos copy whatever data is available even if some is missing. Read here for more information on how PowerPhotos performs partial copies.

Original When you import a photo into your Photos library, that photo is called the “original” and is never modified after being imported into the library. When you edit a photo in your library, Photos create a separate copy of the photo and applies the edits to that copy of the photo. You can later use the “Revert to Original” menu item to discard the edits and display the original photo again.

It's important to note that PowerPhotos does not use the term “original” when talking about duplicate photos, because there is no solid way to define which of a group of duplicates might be considered the “original”. Instead, PowerPhotos chooses a “keeper” and the rest of the duplicates are marked to be trashed.

Referenced Photo Normally when you import photos into your library, Photos makes its own copies of those photos and stores them internally in the library package. In the Photos settings window, there is an option labelled ”Copy items into Photos library” which is on by default. If you uncheck that checkbox, then rather than making its own copies of imported photos, Photos will instead just reference the original photo in whatever folder it was in at the time you imported it. Photos that are not imported as references are typically called “managed” photos.

Referenced photos have the advantage that you can keep your photos organized in an external folder and organize them using Photos as well, but without having to keep two separate copies of the photo on disk. The disadvantage is that if you delete or move the photos from the folder they're located in, then Photos may lose track of them and no longer be able to edit, export, or share copies of those photos.

Shared Albums Shared Albums (not to be confused with iCloud Shared Library) allow you to create custom albums and add photos to them to share them with other people. Shared albums are stored separately from your Photos library, unlike regular albums and folders that are part of the library itself. Shared albums do not count against your normal iCloud storage, but there are limits to how many photos you can put in a shared album, the copies of the photos in the album get scaled down from the original size, and shared album photos cannot be edited like photos in your library. Read more on Apple's website about how to work with shared albums.

System Library You can have multiple Photos libraries set up on your Mac, but at any given time only one of them can be designated the “System Library”. The system library will be the one that appears in most other applications, e.g. when they provide a photo picker to insert photos from your library. The system library is also the only library that can have iCloud Photos enabled. You can switch the system library via the Settings window in the Photos app.