Division of the Tanakh

Tanakh תנך (Bible in hebrew - Old Testament)
  - from the initial letters:

• תורה Torah - aws, doctrine, theory, the basis of science;
  
• נבים Nevi'im - prophets, soothsayers;
  
• כתבים Ketuvim - poetic books, literature.

[1] Our order of books, the name of the first 5 were taken from the Septuagint. The Septuagint also divided the books of Ezra and Nehemiah (in Tanakh they are connected).
[2] Author of the book.
[3] We have the books of Samuel and the Kings named after the books of Kings and divided. The authors of the book are Samuel Gad and Nathan.
[4] The author of the book of the Kings of Jeremiah, gathered Ezra.
[5] In the Hebrew original, called Chronicle, in the Septuagint this book is called Chronicles and is divided into 2 books.