Genre: "Novella" Books

A novella is a written, fictional and prose narrative, usually longer than a novelette but shorter than a novel.
A novella generally features fewer conflicts than a novel, yet more complicated ones than a short story. The conflicts also have more time to develop than in short stories. They have endings that are located at the brink of change. Unlike novels, they are not divided into chapters, and are often intended to be read at a single sitting, as the short story, although white space is often used to divide the sections. They maintain, therefore, a single effect.
The Science Fiction and Fantasy Writers of America Nebula Awards for science fiction define the novella as having a word count between 17,500 and 40,000. Other definitions start as low as 10,000 words and run as high as 70,000 words.