For Jewish people YHWH is the most holy name of God, as written in the ancient Hebrew language. The language has no vowels, so the pronunciation is not agreed on. However, most academics agree that "Yahweh" is one guess of how to say it, but probably is not correct.
It has also been pronounced as "Jehovah" in English, or "Yehowa" in Hebrew. This is because Hebrew pointing, or vowel symbols, are often put under the YHWH, making יְהֹוָה.
Traditionally, religious Jews do not say this name aloud. This is because it is believed to be too holy to be spoken when there is no Temple in Jerusalem. However, they often use substitutes when referring to the name of the their God. For example, they use HaShem ("The Name") or Shem HaMeforash (“the indescribable Name”).
Today, all three Abrahamic religions (Judaism, Christianity and Islam) say that there is only one God. So, YHWH is often referred to as just "God", or "Allah" (which is the Arabic word for god). However, the Jewish Tanakh refers to other gods in several places – most notably in the versions of the Ten Commandments given at either Mount Sinai or Mount Horeb, and detailed in Exodus (20,2 NIV) and Deuteronomy (5,6 NIV), both of which command the Jews not to worship any other god besides YHWH.
Sometimes the four letters are called the Tetragrammaton, which is Greek for four letters
These four letters are usually JHWH in German, French and Dutch, and either YHWH, YHVH, JHWH or JHVH in English. In some English language Bibles, it is written in all capital letters as "LORD," as in Jewish tradition. Others, such as the Jerusalem Bible use "Yahweh".
Jehovah and Yahweh are the most common English pronunciations of the Tetragrammaton.
The name Jehovah is used by the religious organisation of Jehovah's Witnesses.
- Stanley S. Seidner,"HaShem: Uses through the Ages." Unpublished paper, Rabbinical Society Seminar, Los Angeles, CA, 1987.
-  The Catholic Encyclopedia, Volume 8, 1910 edition, page 329, states: “Jehovah, the proper name of God in the Old Testament."