什么叫「居士」？居士，就是居家之士，也就是在家相信佛法的人，守持五戒奉行十善的人就叫居士。
A layperson is someone who believes in Buddhism, upholds the five precepts, and practices the ten good deeds and who has not left the home-life.

◎ 什么叫「五戒」？
◎ What are the five precepts?

就是杀、盗、淫、妄、酒，五种戒。现在有很多人受过五戒了，这都叫居士了。
They are the precepts against killing, stealing, engaging in sexual misconduct, and taking intoxicants. People who have received the five precepts are called lay people.

◎ 什么叫「十善」？
◎ What are the ten good deeds?

十善是十恶的反面。十恶是什么呢？身有三恶--杀、盗、淫。意有三恶--贪、瞋、痴。口有四恶--绮语、妄言、恶口、两舌，几乎占了十恶的一半。
The ten good deeds are just the opposite of ten bad deeds. The ten bad deeds are: killing, stealing, and sexual misconduct, which are done by the body; greed, hatred, and ignorance, which belong to the mind; and lying, loose speech, harsh speech, and divisive speech, which are committed by the mouth. Notice that the offenses of the mouth account for almost half of the ten.