The Tetragrammaton, Strong's Concordance #H3068, is commonly translated as Lord, God or Jehovah in modern Bibles. Most translations, such as the KJV, NIV, NASB, HBFV and others, capitalize these words (e.g. LORD) when the underlying Hebrew referencing God is (usually) the Tetragrammaton.
YHWH (or YHVH) is the most common proper name of the one true God found in Scripture. The Tetragrammaton occurs 5,410 times in the Old Testament manuscripts according to the 1906 Jewish Encyclopedia. The encyclopedia also states it is found the most in the Psalms (645) followed by the book of Jeremiah (555).
One reason the Tetragrammaton is so important is that it reveals the eternal nature of God's existence. It does so because the letters of the word encapsulate the three tenses of the Hebrew verb "to be." These tenses are "He was," "He is" and "He shall be."
Why No Vowels?
Ancient Hebrew, in its written form, included only consonants and not vowels. Readers supplied the vowels as they read (this is true even today in Hebrew newspapers). Reverence for the divine name led to the practice of avoiding its use lest one run afoul of commands such as Exodus 20:7, Deuteronomy 12:3 or Leviticus 24:16.
Jews (and others) sometimes spell the words God and Lord as "G-d" or "L-rd" in order to avoid writing them out fully. Those who practice Judaism, according to one Web site, do this for the following reason.
"Judaism does not prohibit writing the Name of God per se; it prohibits only erasing or defacing a Name of God . . . Jews avoid writing any Name of God casually because of the risk that the written Name might later be defaced, obliterated or destroyed accidentally . . ." (Judaism 101 on the Name of God).
Profession of Faith
The Shema, which originally consisted of only one verse, is a profession of faith memorized by Jews. It quotes Deuteronomy 6:4 and consists of two references to the Tetragrammaton that is translated as "LORD" in the KJV and other Scriptures.
Hear, O Israel: The LORD our God is one LORD (Deuteronomy 6:4, KJV).
New Testament Usage
The New Testament, even when referencing an Old Testament passage that contains the Tetragrammaton, substitutes a Greek word for God. One example of this is in Matthew 3 that quotes from Isaiah 40.
A voice is calling out in the wilderness, "Prepare the way of the LORD (the Tetragrammaton), make straight in the desert a highway for our God" (Isaiah 40:3, HBFV).
Prepare the way of the Lord (kurios, #G2962), make straight His paths (Matthew 3:3, HBFV).
The apostle Paul also substituted YHWH / YHVH from the Old Testament with Greek designations in his writings. For example, he used kurios for Lord in 1Corinthians 1:31 when quoting Jeremiah 9:23 - 24. He did this again in Romans 4:8 that quoted from Psalm 32:2.
Even Jesus, when he quoted from a passage in the Psalms that originally used the Tetragrammaton, replaced it with a Greek word.
The LORD (the Tetragrammaton) said unto my Lord, "Sit at My right hand until I make Your enemies as Your footstool" (Psalm 110:1, HBFV).
Even David himself says in the book of Psalms, "The Lord (kurios) said to my Lord, 'Sit at My right hand . . .'" (Luke 20:42, HBFV).