A Sefer Torah is not a book. It is a scroll of parchment sheets sewn with sinew and wound on two wooden rollers, written entirely by hand by a trained scribe, a sofer, using a quill and iron-gall ink on skin from a ritually clean animal. The rules governing it are unusually exacting: the columns are ruled in advance, the letter forms and the decorative crowns called tagin are prescribed, nothing may be written from memory, and the divine name once written cannot be erased. The text carries no vowel signs, no punctuation and no chapter numbers, those are all later aids that appear in printed Bibles but never in the scroll.
The consonantal text is conventionally counted at 304,805 letters. A single missing, extra or malformed letter renders the scroll pasul, unfit for public reading, until a scribe repairs it; a scroll beyond repair is buried rather than destroyed. Writing one takes most scribes about a year. In synagogue it is read from a raised platform, tracked with a pointer called a yad so that the parchment is not touched by hand, and chanted rather than spoken.
Reading follows a cycle. The Babylonian communities divided the text into 54 weekly portions, parashiyot, completing it in a year; the communities of the Land of Israel used a triennial cycle with the text cut into far smaller units and finished over roughly three years. The annual cycle won out and is now near-universal, though many non-Orthodox congregations have revived a modified triennial reading. The year ends and restarts in a single service on Simchat Torah, when the last verses of Deuteronomy and the opening of Genesis are read one after the other and the scrolls are carried in circuits around the synagogue.