Peptidoglycan is a vital component of the cell walls in bacteria. It provides structural support and helps maintain the shape of the bacterial cell. This unique polymer is made up of sugars and amino acids, forming a mesh-like structure that protects the bacteria from external pressures and threats. In addition to its protective role, peptidoglycan is also important for the classification of bacteria. Gram-positive bacteria have thick layers of peptidoglycan, which retain a purple stain during laboratory tests, while Gram-negative bacteria have thinner layers and do not retain the stain. This distinction helps scientists understand bacterial characteristics and develop treatments.