Bacillus subtilis became the most studied species in the genus Bacillus due to its natural competence for uptake of extracellular DNA that facilitates simple genetic modification and occurrence of sporulation, one of the first studied bacterial cell differentiation processes. The dormant spores can survive harsh circumstances (high temperature, desiccation, UV, and γ-radiation), predation by microorganisms and macroorganisms, or even extraterrestrial conditions. B. subtilis can be isolated from various environments, from soil to marine habitats, and utilized in various applications from enzyme production and food fermentation to plant biocontrol. B. subtilis is a model microorganism for studying cell division, protein secretion, surface motility (swimming, swarming, and sliding), biofilm development, attachment to plant root or fungal hyphae, secondary metabolite production, cytoplasm exchange via intercellular nanotubes, extracellular vesicle release, and kin-discrimination.