There are four verses in the King James translation of the Bible where the name JEHOVAH appears (Exodus 6:3; Psalm 83:18; Issiah 12:2; and Issiah 26:4). The 1901 American Standard Version (ASV) contains 5,761 references of this name and the uses of it in a few other older English translations look much the same. Who is JEHOVAH and why does this name not appear in most other translations?
To get to the answer, we need to take a brief stroll through some textual history as well as the history of the personal name of God.
The Hebrew language is one controlled and shaped by the spoken word, unlike English that's driven by the written word. This generally means that how a word is spoken is how it is written. In the days of the writing of the original Old Testament manuscripts (originally written in Hebrew) everything was handwritten and both the ink to write with as well as the materials to write upon were scarce. So the Hebrew words didn't contain as many vowels as one might think. This wasn't too much of a problem because those who could read and speak the language new how to pronounce the words. But as time passed, the language began to be lost.
As the Hebrew language was disappearing some 7th, 8th, and 9th Century AD Jewish scribes called the Masoretes decided to help preserve the pronunciation of the written text. They held such a reverence to God's Word however, that they did not want to do anything that could be construed as adding to the text. Therefore, they came up with a system of dots and dashes above and below the letters that would serve like a road map for pronunciation. In a way, these markings serve like vowels. The Mesoretic Text or the Mesorah as it is often called is still used and appreciated to this day.
When the Masorites came across the tetragrammaton they had a decision to make. The tetragrammaton is the four letter indication for the name so holly that the Jews do not even say it. It's the name less the vowels. When the Jews came across it in the text, they would mentally change it and simply say "The Name." In English this name is YHWH.
Here is the tetragrammaton in Hebrew:
But now lets say Germans and Englishmen are trying to translate this monkeyed up tetragrammaton into English. Even today there is a funny Y-J translation issue and the same was true when early translations like the King James were in the works. In their best efforts, they came up with the word, "Jehovah." It's not actually a real word. Now rather than the name being preserved and unspoken, it had become something warped and freely spoken. Other translations followed the pattern for a while. The truth however, is that Jehovah is by no means the personal name of God. To the best of our knowledge we can say (in the Hebrew) that YHWH is God's personal name and we think it is pronounced as like Yahweh.
Today many Bible translations still make an effort to preserve the tetragrammaton. Many translations will translate it as LORD in all capital letters. Other Hebrew words, such as adonai might be translated as Lord but it's best to refer to the introduction in your Bible to find out how the translators render these various words.
It's a little different, but here's how the tetragrammaton looks today in most Hebrew Bible printings (if it includes the Mesoretic markings at all):