Microscope is an indespensable tool why?

Answer 1

A microscope (literally ~ 'see small') is a device to aid our natural eyesight.

A low power microscope (<40 times) is very useful in inspection of samples, and in dissecting small structures. Such as parts of a flower. Stereo microscopes are good in this region.

From here you go up to medium power 'scopes, up to a few hundred times. You'll now be looking at the grains of sandstone and similar small items. A binocular microscope will be useful, but you'll no longer have stereo presentation.

Much more than a few thousand becomes difficult for a light microscope, for your subjects themselves approach the wavelength of light in size.

Beyond this, electron microscopes rule, and they may not actually look at the specimen directly. They fire a beam of electrons at the specimen, and display the results on a video screen.

But you can have much more fun here, for if the electrons are sufficiently energetic, they can cause secondary emission from the sample, and analysing these emissions can identify the elements in the sample. You'll now be looking at part of an individual grain of a sandstone.

And with an EM microscope it is simple to copy the picture from the video screen.