Some things, like atoms and molecules are way too tiny to look at them using regular optical microscopes. This is where the scanning electron microscope comes into place. It sees the charges of the atoms and then is able to create a map of those charges. The map that results is a representation of those atoms.
Since salt is a crystal, you can see a whole lot of salt cubes in the nanoworld. Fancy a cube? A salt cube? The scanning electron microscope uses beams of electrons to see things up to 1 nm small, which lets you see even individual atoms. Yep, nothing is the same when you zoom in like crazy on them.
Video via Cambridge University.