The Tetragrammaton

 In the Old Testament, God's name is represented with four Hebrew letters

יהוה

This is called the tetragrammaton.  Jewish people do not pronounce this name, partially because of the third commandment not to take the name of the Lord in vain.  Another reason is that during the Roman persecutions of Christians and Jews, the Romans forbade Christians or Jews from saying the name.  

Ancient Hebrew was written with only consonants. It wasn't until about 400 CE that Jewish leaders began to be afraid that people would forget how to pronounce ancient Hebrew, so they started adding vowel markings to show how words were pronounced.  However, since no one had pronounced the name of God for centuries, no one was quite sure of the correct pronunciation. Therefore, instead of adding vowel markings, they left the tetragrammaton without markings and when they see this name, they say the word, "Adonai" which means "Lord".  The translators of the Bible into English have followed this tradition and when they came across יהוה in the Hebrew, they wrote "Lord" in English.  

People who are not Jewish want to try to pronounce the name, so they have come up with different transliterations.  Remember that Hebrew goes right to left.  The first letter " י " is called yod.  Scholars think it was originally pronounced like a Y, but later, particularly by German speaking Jews, it was pronounced as a J. The second and last letters "ה" is called hey.  It is pronounced with an H sound. The third letter "ו" is a vav which used to be pronounced as a W but the Germanic people, and modern Hebrews pronounce it as a V.  So the ancient form (scholars think) had the consonants, Yhwh, while the later Germanic Jews used the sounds Jhvh. It is easy to see how people started to use the names Yahweh or Jehovah.  

But where did the tetragrammaton come from?  It goes back to the story of Moses and the burning bush. When Moses asked what the Children of Israel should call him, he said. "I AM THAT I AM:...Thus shalt thou say unto the Children of Israel, I AM hath sent me unto you." (Exod 3: 14). In reality, Hebrew doesn't really have a word that means "I am" the same way English does.  The word in Hebrew has more of the sense of "come to pass" or "become".  It is the same word used in Genesis when God says, "Let there be light." Anyway, the word in this verse is the 1st person singular form of the verb הוה, spelled אהוה.  Does that look familiar?  It is the 1st person singular form, but they couldn't go around saying "I am" sent me, so they used the 3rd person singular form (he is), which is, you guessed it, יהוה.

So the question is, why did God decide that his chosen people should call him "he is?"  Maybe he was emphasizing that fact that he really exists, unlike the gods worshiped by the other nations. 

But that is not all.  There is a lovely video by a Jewish Christian where he talks about a bunch of other symbols that can be found in the tetragrammaton.  I don't know how scholarly it is, but I thought it was interesting.  Here is the link. He relates the tetragrammaton to the Hebrew words for "Breath" and "love" so that when John says, "God is Love" it is a word play.  I won't reproduce his argument here.  You will just have to watch the video.

One last note.  In the Church of Jesus Christ of Latter Day-Saints, we use the name Elohim to refer to God the Father, and the name, Jehovah, to refer to the premortal Jesus. This distinction is not reflective of how the people of the Old Testament referred to God. They used Elohim as God's title, and Jehovah as God's specific name. The way that Latter-Day Saints associate the two names to the two separate beings is a modern clarification based on latter-day revelation.