croptool.com
What is a "croptool?"
The crop tool is used in the process of
removing
portions of an image to create focus
or strengthen the composition. The crop tool allows you
to select an area of an image and discard everything
outside this area. The tool "trims the fat" off an image,
it deletes the unwanted and keeps the desired portion
of an image.
The crop tool is most commonly used in Adobe Photoshop. The tool is located third from the top in the Photoshop Toolbox, on the left side.
It's the single most powerful tool in the known universe.