Fighting post-truth using natural language processing: A review and open challenges.

•The study describes the problem of fake news phenomena in digital information.•The study provides a systematic review of the state-of-the-art regarding automatic fake news detection.•From the review, the main subtasks involved in automatic fake news detection are detected and classified.•The review covers systems, resources and competitions in automatic fake news detection.•The review outlines knowledge gaps and future challenges related to automatic fake news detection.