Why is bacteria stained for microscopic observation?
Bacteria are stained for better visual observation, to highlight differences, to enhance cell components, to help identify the bacterium, etc.
There are various reasons why staining techniques are used for microscopic observation of bacteria.
Staining is used for primary identification (e.g. differential staining to identify Gram positive and Gram negative bacteria, or acid fast staining for Mycobacterium or Nocardia bacteria).
Staining can also enhance and differentiate internal cell components.