Pixel Dimensions

1. Image Resolution

1.1. has nothing to do with how your image appears on screen, and has everything to do with how your image will print

2. Document Size

2.1. how big the image will be when printed (determined by pixel dimension and size)

3. Pixel Size

3.1. changes the size of the pixels to be able to fit within an inch for maximum printing quality

4. photoshop telling you the width and height of the image in pixels (how many pixels are in our image from left to right, and from top to bottom) as well as the file size