There is one small problem, however. Many new Lightroom users can be confused by Lightroom's reaction to some of their actions. Some seasoned users even get confused on occasion. Here's a typical question I get asked; "I select several images and press 4 to add a 4 star rating. Why does this sometimes add the rating to all the images selected and other times only to my active image?"
The answer lies in the difference between how the Grid view and the Loupe view treat these actions. Although they are both part of the Library module they serve very different purposes. You can think of the grid view like a lawn sprinkler, it gets everything wet. Loupe view is more like a water gun, you aim it at something and only it gets wet. (It's a weak analogy, I know. But hang in there.)
First, let's talk a little about terms. Take a look at this screenshot from the Library module.
This is the grid view. You can see that the border area around the images appears in different shades of gray. Dark gray indicates that the image is unselected. Light gray means the image is selected. When multiple images are selected then the active image is indicated by the lightest gray border. This same scheme is reflected in the filmstrip at the bottom of the window.
You can switch between grid and loupe by clicking on one of the first two icons on the toolbar. You can also use the keyboard shortcuts of G for grid and E for loupe. When you switch to loupe view it is the active image that will appear.
Back to the original question. So why does pressing 4 sometimes add a 4 star rating to all the selected images and at other times only to the active image? The answer lies in how these two views approach organizational tools. Grid works on the entire group while loupe plays favorites with the active image. This behavior applies to nearly everything you do in the Library module. So if I'm in grid view with several images selected and press 5 they ALL get 5 stars.
This behavior is consistent with all of the organizational tools; keywords, color labels, flags, virtual copies, metadata, etc.. If you glance over at the metadata panel while in grid view you can see that Lightroom puts a placeholder in some fields that are different across the images selected.
So, for example, if the Rights Usage Terms are not the same for all the selected images you will see in that field. As soon as you switch to loupe view the panel changes to show only the metadata for the active image (no matter how many are in the selection).
Even the left and right arrow keys respond differently. While in loupe view the left and right arrow keys will cycle through the selected group and make each image in turn the active image. In grid view pressing the right arrow key will jump you to the first image AFTER the selected group.
The big exception to all of this is the develop tools found in the Library module. And this too makes sense since these tools aren't organizational by nature and are really part of the Develop module. They're in the Library module as a convenience.
So whether you are in grid or loupe view, increasing exposure will only effect the active image. Likewise, pressing V will only convert the active image to black & white.
Once you get this difference into your head then the confusion will be gone and you can zip through your shoots like an organizational superhero!