Gram staining is a laboratory technique used to classify bacteria based on the characteristics of their cell walls. This method differentiates bacteria into gram-positive (which retain the crystal violet stain and appear purple) and gram-negative (which do not retain the violet stain and appear red after counterstaining). This classification helps in guiding the appropriate antibiotic treatment and understanding the bacterial structure. It does not determine the species of the organism directly, nor is it used to diagnose cervical cancer.