The Five Precepts were specially formulated by the Buddha for the benefit of His non-monastic lay followers. They aren't meant to be do-or-die vows demanding strict, 100% observance at all times and in all situations. They are rather ideals to be aimed for. The Buddha's teaching is all about developing awareness. No decent person would consider any of the precepts as too difficult or extreme, but the point is that as soon as one takes the precepts upon oneself one is more likely to be aware of those times when heedlessness could easily take over, with all the attendant consequences.

The Eight Precepts should be observed by all 'full-time' Buddhist monastics and by laypeople when on meditation retreat or on Uposatha (lunar observance) days. The Eight Precepts include the Five Precepts, with an alteration to the wording of the third precept; this time the intention is to abstain from any kind of erotic activity. The additional rules are helpful to those trying to focus effort on meditation practice; particularly when on retreat in a monastic environment.