Jehovah is not God's name. Yes, you read that correctly. It did not exist in biblical times. I know what you're thinking, "What?! Why do so many use it?" At least, that's what I was thinking when I first heard the same thing as I was sitting in my Hebrew class. Hear me out, and let me explain.
Hebrew was written without vowels (even though the vowels were pronounced out loud). So, without vowels, Hebrew was only written with consonants.
Some scribes, called the Masoretes, realized that they needed a way to insert vowels into the written language of Hebrew. Otherwise, future generations may not know how to pronounce these words, and eventually the language would be lost. They devised a system of dots and lines (called vowel points) which allowed the reader to determine which vowels to pronounce. (If you want to see what this looks like, look at the picture above. Most of the dots and lines which appear under the block-style Hebrew letters in the picture are vowel points.)
So, how do we know that Jehovah is not God's name? Because Jews did not pronounce God's name. Many scholars think that God's name, which is often pronounced Yahweh, may have actually been Yahveh ("LORD" in the Old Testament of most English Bibles). In other words, some scholars think it was a "W" while others say it was a "V."
Nevertheless, Jews considered God's name too holy to even say it out loud. Instead, they said the word Adonai (which is commonly written "Lord" in the Old Testament of most English Bibles). When the Masoretes put the vowels on the Hebrew letters, they put the vowels from Adonai on the consonants from Yahveh. They did so to remind the reader to say Adonai rather than Yahveh. In Hebrew, vowels follow certain rules and change under certain circumstances. So, this is what it looks like (when I transliterate it into English letters):
YAHVEH (take the consonants from this word)
ADONAI (take the vowels from this word)
Becomes YEHOVAH
Then, years later, scholars who didn't understand what the Masoretes were doing simply read Yehovah, and they came up with Jehovah as the name of God.
In A Theological Miscellany, T. J. McTavish explains,
Pious Jews didn't want to pronounce the holy name of God . . . so they substituted the word Adonai (Lord) . . . In the late Middle Ages, scholars who didn't understand this practice came up with the hybrid form Jehovah (J is pronounced like Y, as in German and other languages). (3)So, Jehovah is not God's name. It didn't exist in biblical times, and it was created out of a misunderstanding of the Hebrew text.
Bibliography:
-McTavish, T. J. A Theological Miscellany: Odd, Merry, Essentially Inessential Facts, Figures, and Tidbits About Christianity. New York, NY: MJF, 2005.