It's an object that reflects light or sound that preserves much of its quality prior to contact with the mirror. They can vary as to wavelengths and what gets filtered.
Mirrors are used by most people. The reasons and degrees fluctuate as do the results.
Some give a relative dead on image. Others distort such as convex, like a fisheye, makes an image more distant and usually have a warning that objects are closer than they appear. They do give a wider field of vision. Concave are inward and give different images depending on distance.
Shape size etc can give nuances as to effect. Reflection is not just reflection.
But, mostly, I think it's attitude that affects mirrors, at least as far as people looking at themselves and others.
In Hollywood, mirrors are handy tools of the trade. Makeup and lighting combine with reflection to create effect, whatever the goal may be. It can minimize the bumps and pores even before airbrushing.
There are those obsessed with image. But we never exactly see ourselves as others do.
It is said mirrors show the truth. Others claim it's merely literal reflection, just an image that never reveals anything completely.
Perhaps it depends on the eye of the beholder. People see what they want to see.
So truth can be had. But it takes time and circumstances to see.
You may have to look twice.
There are other types of mirrors. They reflect sound and matter.
But that is another matter altogether.
Mirrors as clues might sum it up. Give yourself a chance to see.