Tetragrammaton
Tetragrammaton (from the Greek τετραγράμματον, meaning '[word of] four letters' (tetra "four" + gramma (gen. grammatos) "letter"), [1] refers to יהוה, the name of the God of Israel, written with four letters, as written in the Hebrew Masoretic Text where it appears over 6,800 times.
The letters themselves are (reading from right to left):
Hebrew Letter name Pronunciation י Yodh "Y" ה He (pronounced "hey") "H" (or sometimes silent) ו Vav "V" ה He "H" or silent
Biblical Hebrew often omits vowel sounds from its writings, which would be shown in English.
These four letters are usually transliterated from Hebrew as JHWH in German, French and Dutch, and YHWH in English. This was variously rendered as "Yahweh" or "Jehovah", since in Latin there was no distinct lettering to distinguish 'Y' from 'J', or 'W' from 'V', and the Hebrew does not clearly indicate the omitted vowels. In English translations, it is often rendered in all capital letters as "LORD", following Jewish tradition which reads the word as "Adonai" ("Lord") out of respect for the name of God and the commandment not to take the name of God in vain.
See "Historical overview" at Yahweh.