Hebrew Aseret haDibrot, "the ten words" — from which the alternate English term Decalogue (Greek deka, "ten" + logos, "word"). The ten foundational commandments given by God directly to Israel at Mount Sinai (Exodus 20:1-17, repeated in Deuteronomy 5:6-21). Written by God's own finger on two stone tablets (Exodus 31:18, 32:16). The first four govern human relationship to God; the last six govern human relationships. Christian tradition numbers them slightly differently (Reformed/Eastern numbering versus Catholic/Lutheran numbering), but the ten items are the same.
The Ten Commandments are the moral backbone of biblical ethics. Five observations. (1) Grounded in redemption. The preface — "I am the LORD your God, who brought you out of the land of Egypt, out of the house of slavery" (Exodus 20:2) — precedes any command. Obedience is the grateful response of a redeemed people, not the condition of redemption. Christians read this through the cross: we keep the commandments because we have been redeemed, not to earn redemption. (2) Moral, not ceremonial or civil. Reformed theology distinguishes three types of OT law: moral (the Ten Commandments), ceremonial (temple, sacrifices, food laws — fulfilled in Christ), and civil (Israel's national constitution — expired with the theocracy). The moral law, rooted in God's unchanging character, remains binding on all people. (3) Two tables, one law. Tablet one: no other gods, no idols, the name holy, the Sabbath. Tablet two: honor parents, no murder, no adultery, no theft, no lying witness, no coveting. Jesus summarized the two tables as love of God and love of neighbor (Matthew 22:37-40). (4) Deeper than the surface. Jesus pressed the commandments into their full scope: adultery includes lustful gazing (Matthew 5:28); murder includes hateful thoughts (5:22). The commandments are not a minimum moral code; they are a searchlight into every corner of the heart. (5) Guide, not path. The Decalogue does not save anyone (nobody keeps it perfectly); it reveals sin (Romans 3:20) and drives us to Christ. Post-conversion, it remains the pattern of love in a sanctifying life (Romans 13:8-10).