Sometimes when you edit a vector image, you need to crop some
objects. In bitmap based editor, you can easily do it usually by
Shift+C. But how to do that in Inkscape? In Inkscape, even you can crop
some objects by non-rectangular shape. I will show you some guides.
To crop an object, you will need another object. Actually, it is not a crop feature. It is just a Clip tool. You can access it from menu Object > Clip > Set Clip. Let assume we have 2 rectangle object like this (before). We can do Set Clip so the outer rectangle cut off into the size of the inner rectangle.
We can do cropping in star shapes. We can crop in triangle shapes. And so on. Just prepare your second shape.
More Advanced Cropping
You can crop a real bitmap image with same technique. Drag and drop a PNG image into Inkscape and do Set Clip. You can choose the crop shape. See picture below.
Remember that you can not crop an image with more than one single shape concurrently. You should crop a shape one by one.
You can get your original shapes if your cropping goes wrong. Just select the cropped object then use menu Object > Clip > Release. You will get the original object and the second object.