The crop tool has a very easy keyboard shortcut to remember, so you'll rarely need to bother with selecting it from the toolbox. The shortcut for activating the crop tool is C. The crop tool in Photoshop Elements can actually do much more than crop your images. The crop tool can be used to increase your canvas size, straighten, rotate and resample images.
Let's start by exploring the most common use of the crop tool... cropping, of course! Open any image and select the Crop tool. Notice in the options bar you have spaces to fill in the desired width, height and resolution for the final cropped image. To the far left of the options bar, you can select from several crop tool preset options. I'll go over the crop tool options and presets a bit later, but for now, if you see any numbers in the crop tool options, press the clear button on the options bar to remove them
There's no need to be precise when making the first crop selection, because you can edit your selection before committing to the crop. If you want exact precision however, you will want to switch to a crosshair cursor. At any time, you can toggle from standard to precise cursors by pressing the Caps Lock key. This works with the painting tools as well. Try it out. You may find that the precise cursor is hard to see in some backgrounds, but it's nice to have the option when you need it.
The Crop Shield and Adjusting the Crop Selection
Pick which ever cursor preference you like and drag out a crop selection on your image. When you let go, the crop marquee will appear and the area to be discarded is shielded with a gray screen. The shield makes it easier to visualize how the cropping affects the overall composition. You can change the shielded area color and opacity from the options bar after you make a crop selection. You can also disable the shading by unchecking the "Shield" checkbox.
Notice the squares on the corners and sides of the selection marquee. These are called handles because you can grab onto them to manipulate the selection. Move your cursor over each handle and you'll notice it changes to a double pointing arrow to indicate that you can resize the crop border. Make some adjustments to your crop selection now using the handles. You'll notice if you drag a corner handle you can adjust the width and height at the same time. If you hold the shift key down while dragging a corner handle it constrains the height and width proportions.
Moving and Rotating the Crop Selection
Now move your cursor inside the selection marquee. The cursor changes to a solid black arrow indicating that you can move the selection. Holding the shift key while you move the selection constrains your movements.
But that's not all... move your cursor to just outside one of the corner handles and you'll see it change to a double pointing curved arrow. When the curved arrow cursor is active you can rotate the selection marquee. This allows you to crop and straighten a crooked image at the same time. Just align one of the crop edges to a portion of the image that should be horizontal or vertical, and when you invoke the crop, it will rotate the image to conform to your selection. The center point on the crop marquee determines the center point to which the marquee is rotated. You can move this center point to change the center of rotation by clicking on it and dragging.
Completing or Canceling Crop
If you change your mind after you've made a crop selection, you can back out of it by pressing Esc. To commit to your selection and make the crop permanent, you can press Enter or Return, or simply double click inside the selection marquee. You can also use the check mark button on the options bar to commit to the crop, or the circle-slash button to cancel the crop. If you right click in the document where you have made a crop selection, you can also use the context sensitive menu to finish the crop or cancel the crop.
Cropping Aspect Ratio
As you work with the crop tool, take a look at the options bar. You'll see there are options here for setting the aspect ratio, width, height, and resolution. Aspect ratio is the relationship of an image's width to height, or its proportions. The crop tool offers several aspect ratio presets for common photo print sizes such as 4x6, 3x5, 5x7, and so on. The "Use Photo Ratio" option will keep the aspect ratio the same as what you started with.
You may have noticed that Elements does not offer both portrait and landscape orientations of each aspect ratio. This is not necessary because you can easily swap the width and height values for the crop tool. By clicking on the double pointing arrows between the Width and Height fields on the options bar, the numbers will swap. When you crop using any of the aspect ratio options, you can size the crop marquee to any size, but it will always retain the aspect ratio you've chosen.