A book is a set

When writing systems were invented/created in ancient civilizations, nearly everything that could be written upon—stone, clay, tree bark, metal sheets—was used for writing.The study of such inscriptions forms a major part of history. The study of inscriptions is known as epigraphy. Alphabetic writing emerged in Egypt . The Ancient Egyptians would often write on papyrus, a plant grown along the Nile River.

The word book comes from Old English “bōc” which (itself) comes from the Germanic root “*bōk-“, cognate to beech. Similarly, in Slavic languages (for example, Russian, Bulgarian, Macedonian) “буква” (bukva—”letter”) is cognate with “beech”. In Russian and in Serbian and Macedonian, another Slavic languages, the words “букварь” (bukvar’) and “буквар” (bukvar), respectively, refer specifically to a primary school textbook that helps young children master the techniques of reading and writing.