Lots of people are confused by Lightroom.
Some people wonder where Lightroom stores its photos. Some wonder what the catalog is about, some people don’t understand why their photos look ‘normal’ outside of Lightroom, what are the exclamation marks, and why is there no save option!
One simple answer to all of these questions, is that Lightroom is a pointer. It points to where your photos are and stores that information inside the catalog. It stores location information (i.e. folder location on hard drive) and shows the photo from that location. This also explains the ! (exclamation mark) symbols if the photos are moved outside of Lightroom. Edit information is also stored and applied to the photo in Lightroom, which explains why a photo looks ‘normal’ when viewed in Finder or Windows Explorer. It also explains that lack of a save button, it doesn’t need one to show your edited photos.
All of this information is stored in your Catalog file. This is the most important file. It stores all the information about your photos in it, but doesn’t store your photos. This file should be backed up regularly and looked after! It is all your edits and storage information for finding, viewing and editing your photos whilst using Lightroom.