Today’s Question: What is the hierarchy in Lightroom Classic for the catalog, folders, and collections, and how they interplay?
Tim’s Quick Answer: The catalog in Lightroom Classic represents all of your photos and the information about those photos. Folders represent the actual folders on your hard drive, and therefore represent your actual storage structure. Collections provide a way to group photos together in ways that go beyond the folder structure, such as grouping photos together from various folders for a particular project.
More Detail: The catalog is at the foundation of a workflow for organizing, optimizing, and sharing your photos using Lightroom Classic. I strongly recommend using only one catalog to organize all of your photos. Taking this approach means that you don’t really need to think about the catalog directly, but rather can simply think of Lightroom Classic as being at the center of your workflow.
Folders in Lightroom Classic are a direct reflection of the folder structure for your photos on the hard drive. When you import existing photos from a hard drive, for example, the folder structure for those photos on the hard drive will be reflected in Lightroom Classic. If you make changes to the folder structure within Lightroom Classic, such as by renaming or moving a folder or creating a new folder, those changes will be reflected on your hard drive as well.
It is important to note, by the way, that any folder changes should be made within Lightroom Classic, which will result in those changes being reflected in the operating system. If you make changes directly through the operating system, those changes will not be reflected in Lightroom Classic, and in fact you will end up with folders and photos that are missing because they are no longer found where they are expected.
Collections represent the organizational feature that many photographers get confused by. A collection simply provides a way to group photos together in a way that goes beyond the folder structure on your hard drive. Collections are not reflected in the operating system at all, as they only exist within Lightroom.
You can use collections in a variety of different ways depending on your specific needs. For example, if you wanted to have an easy way to reference favorite photos from a single trip, you could add those photos to a collection within Lightroom Classic.
One of the great things about collections though is that they can contain photos from a variety of different folders. For example, if you were creating a photo book featuring your favorite images from a variety of different trips, a collection is a great way to organize those photos. You can add photos to a collection from multiple folders, but adding a photo to a collection doesn’t create a copy of the source image on the hard drive. The image in the collection is simply a reference to the original photo, similar to a saved search result.
Another great feature of collections is that you can enable synchronization to the Adobe Creative Cloud for a collection of photos. Those photos can then be viewed and shared using the Lightroom app on your mobile device, or by signing in with your Creative Cloud account at https://lightroom.adobe.com/.