Medieval Hebrew has many features that distinguish it from older forms. These affect grammar, syntax, sentence structure, and also include a wide variety of new lexical items, which are usually based on older forms.
The pressing need to express scientific concepts from ancient Greek and medieval Arabic philosophy in Hebrew motivated the creation of many or most of these new forms. Many have direct parallels in medieval Arabic. The Ibn Tibbon family, and especially Samuel ben Judah ibn Tibbon were personally responsible for the creation of much of this form of Hebrew, which they employed in their translations of scientific materials from the Arabic. As time went on, this form of Hebrew was used for many original compositions as well.
Besides works that dealt with medieval philosophy and science, special forms of Hebrew are found in the highly developed genre of medieval Hebrew poetry called piyyut.
The core of the Tanach (the Hebrew Bible) is written in Classical Hebrew, and much of its present form is specifically the dialect of Biblical Hebrew that scholars believe flourished around the 6th century BCE, near the Babylonian exile.
Hebrew, long extinct outside of Jewish liturgical and scholarly purposes, was revived as a literary and narrative language by the Haskalah (Enlightenment) movement of the mid-19th century.
Hebrew was employed as both a written and spoken language until the fall of Jerusalem in 587 BCE.
Hebrew was often thought to be the language of the angels, and indeed, of God.
Hebrew had not been a spoken language for two millennia, and yet at the end of the 19th century, European Jews dreaming of a cultural renaissance in Palestine began to resurrect the language.