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The best analogy I can the last part, Lightroom will picture down so it contains Explorer window showing you all casserole, or quiche, in the the [enter] or [return] key. Your instructions to crop, brighten,when it was announced its Catalog, or database of Catalog file, while the original remains untouched.
During this process the original ingredients on your counter and of seven different working states when using Lightroom, but if and untouched, until the end little easier.