other commenters have covered the first two parts of your question quite well already. old books written in the 1900s are books that were written between 1900 and 1999. back then, books mostly got printed on paper, which is kinda like a screen, except it only shows one thing, ever, so you need lots of these “papers” to show a whole book. these papers would all be attached together using string and/or glue. books covered a wide variety of topics. they could be educational or describe made up stories. they could be small enough to fit in a pocket, or so big you need two hands to carry them. notable trends in books during the 1900s included the flourishing of science fiction, a kind of made up story where scientific or technological advancements play a prominent role, buoyed by technological progress and optimism about the future in the first half of the 20th century. the 1900s also saw a great deal of attention put to comic books, which, unlike more traditional books, tell stories using small pictures with text to show dialogue, rather than just text. comic books were well known for their depiction of heroic characters with unusual abilities such as Wonder Woman, or Spider-Man.
other commenters have covered the first two parts of your question quite well already. old books written in the 1900s are books that were written between 1900 and 1999. back then, books mostly got printed on paper, which is kinda like a screen, except it only shows one thing, ever, so you need lots of these “papers” to show a whole book. these papers would all be attached together using string and/or glue. books covered a wide variety of topics. they could be educational or describe made up stories. they could be small enough to fit in a pocket, or so big you need two hands to carry them. notable trends in books during the 1900s included the flourishing of science fiction, a kind of made up story where scientific or technological advancements play a prominent role, buoyed by technological progress and optimism about the future in the first half of the 20th century. the 1900s also saw a great deal of attention put to comic books, which, unlike more traditional books, tell stories using small pictures with text to show dialogue, rather than just text. comic books were well known for their depiction of heroic characters with unusual abilities such as Wonder Woman, or Spider-Man.
I don’t think we’ve quite reached the point in human development where we need to explain to people what books are.