Soferut is the Jewish scribal discipline of producing STaM, an acronym gathering the three categories of sacred text Jewish law holds must be handwritten according to exacting rules rather than printed: sifrei Torah, complete Torah scrolls read publicly in synagogue; tefillin, the small leather boxes containing scriptural passages bound to the arm and head during weekday morning prayer; and mezuzot, the parchment scrolls affixed inside a small case to the doorposts of a Jewish home.
A sofer, the trained scribe who produces these texts, writes by hand using a quill, traditionally from a kosher bird, and specially prepared ink on parchment made from the skin of a kosher animal, following an unbroken chain of transmitted rules governing everything from the precise letterforms and their required decorative crownlets, tagin, on certain letters, to the exact spacing between words and the treatment of specific words and divine names, rules a sofer studies for years under an experienced teacher before being considered competent to produce texts intended for actual religious use. The standard of accuracy demanded is unusually severe even by the standards of religious scribal traditions generally: a single letter written incorrectly, touching an adjacent letter, or malformed in a way that changes or obscures its identity can invalidate an entire Torah scroll for public liturgical use, however minor the error looks to an untrained eye.