1. Staphylococci and Streptococci are two common types of bacteria that can be differentiated based on their microscopic morphology as seen by Gram stain. Staphylococci are typically round-shaped bacteria that appear in clusters, resembling a bunch of grapes. They stain purple or blue under Gram stain, indicating that they have a thick peptidoglycan layer in their cell walls, which helps them resist the decolorization step (Veras da Fonseca et al., 2020). Additionally, they may also possess a thick polysaccharide capsule that can be observed under the microscope as a clear halo surrounding the cells.