Lay people tend to live by the five what?
Śīla refers to overall principles of ethical behavior. There are several levels of sīla, which correspond to "basic morality" (five precepts), "basic morality with asceticism" (eight precepts), "novice monkhood" (ten precepts) and "monkhood" (Vinaya or Patimokkha). Lay people generally undertake to live by the five precepts, which are common to all Buddhist schools. If they wish, they can choose to undertake the eight precepts, which add basic asceticism.