Here's an example of how cropping and resizing can improve the way you display your pictures.
In the top example, the pictures' original sizes vary, being either more horizontal or more vertical.
In the bottom example, the pictures are cropped and resized to be a uniform shape, and they're all slightly bigger. (Another help is that they have sharper frame formatting.)
Important If you crop and then enlarge a picture, make sure that the picture has a high enough resolution that it won't appear blurry when projected. Resolution refers to the density of pixels, the small dots of color that make up bitmap images. When you preview your slides in a slide show, you can tell whether the images are sharp or not. For more about picture resolution, see the Quick Reference Card at the end of the course.