Acid-fast staining is a laboratory technique used to identify acid-fast bacteria, such as Mycobacterium tuberculosis and other related species, which have a waxy outer layer in their cell wall that makes them resistant to traditional staining methods. The staining process involves the use of special acid-fast dyes, such as Ziehl-Neelsen or Kinyoun stain, which can penetrate the waxy layer and stain the bacteria. Once stained, the bacteria can be viewed under a microscope for identification and diagnosis of diseases such as tuberculosis and leprosy.