Cropping means to eliminate all parts of the image that aren’t important to its composition.
Cropping is especially important in Photoshop. Each pixel, no matter what color, takes up the same amount of information, so cropping eliminates unneeded pixels and saves on file size and processing time. For that reason, you should crop images before you start working on them.
Use the Crop tool.
Select an area with the Marquee tool and choose Image→Crop.
Select and Display Tools
A. Tools panel
B. Active tool
C. Hidden tools
D. Tool name
E. Tool shortcut
F. Hidden tool triangle
To crop an image by using the Crop tool, follow these steps:
Press C to access the Crop tool and drag around the area of the image you want to crop to.
If you need to adjust the crop area, drag the handles in the crop-bounding area.
When you’re satisfied with the crop-bounding area, double-click in the center of the crop area or press the Return or Enter key to crop the image.
If you want to cancel the crop, press the Esc key.