"Gram-positive" refers to a classification of bacteria that retain a purple color when subjected to the Gram stain test. This characteristic is due to their thick peptidoglycan layer in the cell wall, which traps the crystal violet dye used in the staining process. Examples of Gram-positive bacteria include Staphylococcus aureus and Streptococcus pneumoniae, which can be significant in both health and disease. These bacteria are often associated with various infections and can be treated with specific antibiotics, such as penicillin. However, some Gram-positive bacteria have developed resistance to these treatments, leading to challenges in medical care. Understanding the properties of Gram-positive bacteria is crucial for effective diagnosis and treatment.