A textbook or coursebook is a manual of instruction in any
branch of study. Textbooks are produced according to the demands
of educational institutions. Although most textbooks are only
published in printed format, many are now available as online
electronic books and increasingly, although illegally, in
scanned format on file sharing networks. The ancient Greeks
wrote texts intended for education. The modern textbook has its
roots in the standardization made possible by the printing
press. Johannes Gutenberg himself may have printed editions of
Ars Minor, a schoolbook on Latin grammar by Aelius Donatus.
Early textbooks were used by tutors and teachers, who used the
books as instructional aids (e.g., alphabet books), as well as
individuals who taught themselves. The Greek philosopher
Socrates (469-399 B.C.) lamented the loss of knowledge because
the media of transmission were changing. Before the invention of
the Greek alphabet 2,500 years ago, knowledge and stories were
recited aloud, much like Homer's epic