Experts estimate that about 90,000 manuscripts have been written in the Hebrew language. The National Library (NLI) collection includes ~8,000 of them, along with ~2,500 manuscripts in the Arabic language and ~800 in other languages.
In addition to the physical manuscripts, since the 1950s the NLI has been operating the Institute for the Photography of Hebrew Manuscripts. The institute collects microfilm copies of manuscripts found in other collections across the world, both private and public. The institute currently has over 76,000 microfilm reels and thousands of digital scans, which comprise over 90% of the known Hebrew manuscripts in the world. All of these are available for perusal to researches and other interested parties.
Among the most important manuscripts found in the NLI are: Maimonides's original Mishnah commentary, theological manuscripts by Isaac Newton and dozens of rare significant Muslim works.