Gram-positive bacteria are a group of microorganisms that are characterized by their thick cell walls that retain crystal violet dye stain when undergoing the Gram staining process. There are several synonyms that can be used to refer to this group of bacteria, including Firmicutes, low G+C Gram-positive bacteria, and positive cocci. Firmicutes are a phylum of bacteria that includes many gram-positive organisms such as Bacillus, Clostridium, and Staphylococcus. Low G+C Gram-positive bacteria are named for their lower G+C DNA content and include Listeria, Streptococcus, and Enterococcus species. Positive cocci are spherical-shaped bacteria that can be found in clusters, pairs, or chains; examples include Staphylococcus and Streptococcus.