A microblogging novel, also known as a micro novel, is a fictional work or novel written and distributed in small parts, defined by the system it is published within. A 'Twitter novel' would be published in chapters of 140 characters or less, and a 'Facebook novel' might be limited by Facebook's 'read more' limitations of 300 characters.
Micro novels are related to blog fiction, which is published in blog format.  Another related phenomenon is the cell phone novel where installments are sent out to readers via SMS; this type of publishing originated in Japan. Micro novels have also been known to be published through email. Similar manifestations include flash fiction, a work of fiction completed in 1000 words or less, where the publishing medium is irrelevant.