Notebook is a style of writing where people jot down what they have thought or heard at the spur of moment.
He called his notebooks "waste books," using the English book-keeping term.
The notebooks of scientists, such as those of Michael Faraday and Charles Darwin, can reveal the development of their scientific theories.
Leonardo da Vinci's notebooks contain his writings on painting, sculpture, architecture, anatomy, mining, inventions and music, as well as his sketches, his grocery lists and the names of people who owed him money.
In Chinese literature, "notebook" or biji is a distinct genre, and has a broader meaning.