"So no, the Masoretes did not add previously non-existing vowels to the Hebrew Bible, but left us notations about what the Hebrew words may have sounded like (namely "David" in stead of "Dod", and so on)."
"The name Masorete(s) obviously doesn't occur in the Bible itself because the Masoretes, the folks who added pronunciation symbols (the Masorah) to the traditional Hebrew text of the Bible, began to be active in the second half of the first millennium after Christ. Their work and intentions, however, are of enormous importance to students of the Bible because:"
"The name Masoretes is like the epithet Explorers; it describes a group of completely different people who shared one particular quality without being unified by that quality. The Masoretes were Hebrew scholars who worked over the span of a few centuries and in a geographic area ranging from
Babylon to
Palestine and from Europe to Yemen. These Masoretes were part of the larger Hebrew academia..."
"The formal Hebrew Bible of today is based on the Leningrad Codex, which is a Tiberian Masoretic Text of 1009 AD, which is a copy of a text that was produced by the Ben-Asher family, and they were Masoretes living and working in Tiberias in
Galilee..."
"
Then, the Ben-Ashers were not the only ones working with that now so famous Masoretic system, because the Ben-Ashers were at much documented odds with another Tiberian family, namely the Ben-Naphtali family, and that's just one competitor we know about, working within the same system.
A whole other famous Masoretic system was the Babylonian system, or rather: were the Babylonian systems, which consisted of a simple and a complex one and at least six more identifiable styles. A third system (or again, rather a cluster of various systems) is called "Land of Israel" because it's referred to in some 11th century European text that discusses the diacritics of the phrase ארץ ישראל (
erets yisrael), meaning land of Israel. It's not clear where this particular cluster of systems originated but "most people believe that the Land of Israel system is the earliest system" (says Joel M. Hoffman in
In The Beginning).
A fourth system, again with internal variations, uses Tiberian symbols but writes the Land of Israel system. A fifth system was developed in Yemen, and a sixth system was developed by scholars of the East
Syriac language area..."