Rectangular Selection Tool

The Rectangular Selection Tool located at the top left portion of the Gimp Toolbox, can be used to select rectangular sections of the image that you are working with.

The Mode section of the Options Box that comes with this tool allows replacement of the current selection, add to the current selection, subtract from the current selection, or intersect with the current selection.

Also there is the option to Feather the Edges or toggle with the Auto Shrink Selection. Free Select, Fixed Size, and Fixed Aspect Ratio control the shape and size of the selection that is under construction.

Here the Rectangular Selection Tool is used to select the middle portion of this picture. From this step shown in the picture, rotate, resize, transform, flip, manipulate, and do many other editing options to this one selection.

There are many options to work with in the Select Menu that is on the Toolbar above the image.