The Five Precepts
Everyone who wants to formalize their commitment to the Dharma, after taking The Triple Refuge makes a pledge to obey the Five Buddhist Precepts. These, in addition to additional ovbious rules of moral conduct make up what would be the buddhist equivalent of the "Ten Commandments", except that they are not commandments, and there are only five that are generally observed by lay practitioners.
They are:
The First Precept: No Killing.
The spirit of this precept is to nurture a heart of compassion. We should not, by intent, wish harm or death upon another living being, whether human or animal. We should not take delight in the sufferings of others, but rather regard them with compassion. We ourselves should not commit any act of killing; we should not advise others to kill; and we should not approve of, or participate in, any act of killing. To behave otherwise would result in the breaking of this Precept.
The Second Precept: No Stealing.
The spirit of this precept is to prevent greed and promote honesty and contentment. If something is not given to us, we may not take it. We should not take the property of others by force, by stealth, or by fraud. This prohibition includes tax evasion and the failure to pay fees.
We should treat the property of others with respect and care, and see it as more important than our own property. We ourselves should not commit the act of stealing; we should not advise others to do so; and we should not approve of, or participate in, any acts of stealing. To behave otherwise would result in the breaking of this Precept.
The Third Precept: No Sexual Misconduct.
Desire is the cause of our suffering in the cycle of birth and death. It is also a great obstacle to our practice on the path of Awareness and Understanding. We should make a strong resolve to transform these kinds of desires into compassion for all beings.
If you have a family, sexual activities should take place only between you and your spouse. You should respect your commitments and the rights of others, and preserve your energies for the practice of the Way.
We ourselves should not commit any act of sexual misconduct; we should not advise others to do so; and we should not approve of or participate in acts of sexual misconduct. To behave otherwise would result in the breaking of this precept.
The Fourth Precept: No Lying.
The spirit of this precept is to practice positive and constructive speech for the benefit of living beings. We should not say things we know to be untrue, either for personal benefit or to impress people. We should use our speech to promote harmony and understanding, guiding others toward kindness and wisdom. Whenever possible, we should introduce the Buddha's teachings to others and encourage them to walk that path. We ourselves should not practice false speech; we should not instruct others to do so; and we should not approve of, or participate in, acts of speaking untruthfully. To behave otherwise would result in the breaking of this Precept.
The Fifth Precept: No Taking of Intoxicants.
This is a precept of prevention. Intoxicants can delude and confuse the mind, harming our seeds of wisdom. The Buddha established this precept to prevent the breaking of the other four Precepts when one loses good conscience after intoxication. Intoxicants include alcohol, drugs, and the like. We ourselves should not take intoxicants; we should not advise others to do so; and we should not approve of, or participate in, the act of taking intoxicants. To behave otherwise would result in the breaking of this Precept.
There are instances, under certain circumstances, when a Precept might not be strictly observed because harm might be done to others if the precept were strictly upheld. For example, when you attend a wedding ceremony or a birthday party for non-Buddhist friends, you might be expected to drink some wine to celebrate the occasion. If you insist on observing the Precept against taking intoxicants instead of joining the celebration, others might think: "Buddhist rules are so strict and forbidding, I don't think I'll ever want to become Buddhist." If we make others feel this way, we might be ruining their opportunity to learn and benefit from the Buddha's teachings. Therefore, the harm you might do by observing this Precept could far outweigh any virtue you might accrue from upholding it..
In every situation, you should consider the spirit of the Precepts and consider the best ways to apply them in different situations and in the company of different people. In the example I just referred to, if you were to drink a little wine to celebrate with everyone else -- but not to the point of getting drunk -- you would not be regarded as violating a Precept because of the time and place in which the behavior occurred. On the other hand, if you were looking for a chance to get drunk, you would be regarded as violating a Precept, not modifying it for the benefit of living beings.