Then Moses said to God, “If I come to the people of Israel and say to them, ‘The God of your fathers has sent me to you,’ and they ask me, ‘What is his name?’ what shall I say to them?” God said to Moses, “I AM WHO I AM.” And he said, “Say this to the people of Israel, ‘I AM has sent me to you.’” God also said to Moses, “Say this to the people of Israel, ‘The LORD, the God of your fathers, the God of Abraham, the God of Isaac, and the God of Jacob, has sent me to you.’ This is my name forever, and thus I am to be remembered throughout all generations. Exodus 3:13-15

The term Tetragrammaton (from Greek meaning “[a word] having four letters”) refers to the proper name of the God of Israel YHWH (Hebrew: יהוה‎) used in the Hebrew Bible.

The Tetragrammaton occurs 6,828 times in the Hebrew text. It does not appear in the Song of Songs, Ecclesiastes, or Esther. It first appears in the Hebrew text in Genesis 2:4.

This has been variously rendered as “Yahweh” or as “Jehovah”, based on the Latin form of the term, while the Hebrew text does not clearly indicate the omitted vowels.

In English translations, it is often rendered in capital and small capital letters as “the Lord”, following Jewish tradition which reads the word as “Adonai” (“Lord”) out of respect for the name of God and the interpretation of the commandment not to take the name of God in vain.

The word LORD, when spelled with capital letters, stands for the divine name, YHWH, which is here connected with the verb hayah, “to be” in verse 14

It has often been proposed that the name YHWH is etymologically a third person masculine imperfect verb form derived from the Biblical Hebrew “to be”, which has (h-w-y) as a variant form. This would connect it to the passage in verse Exodus 3:14, where God gives his name as translated most basically as “I am what I am” (or “I will be that which I now am” or “he who causes to exist” or “who gives life” or “he who is, who exists”).

The biblical law does not prohibit the use of the Name, but it warns against “misuse”, “blaspheming” or in ordinary terms, “taking lightly” the Name of YHWH. The Biblical texts suggest the people of the Bible—including the patriarchs—used the Name of YHWH.

Jehovah’s Witnesses incorrectly believe this is God’s name (like Ben or Harry) and think calling God any other name is a sin. Many times people were named after incidents (Moses – “he who was drawn from the water”) or feelings (Judah – “praise the Lord”). God’s name explains who he is, but since he is so many things, calling him God, the Lord, Lord God Almighty, Adonai speaks to his powerful wonder.

(From Wikipedia)