  In recent years, disinformation including fake news, has became a global
phenomenon due to its explosive growth, particularly on social media. The wide
spread of disinformation and fake news can cause detrimental societal effects.
Despite the recent progress in detecting disinformation and fake news, it is
still non-trivial due to its complexity, diversity, multi-modality, and costs
of fact-checking or annotation. The goal of this chapter is to pave the way for
appreciating the challenges and advancements via: (1) introducing the types of
information disorder on social media and examine their differences and
connections; (2) describing important and emerging tasks to combat
disinformation for characterization, detection and attribution; and (3)
discussing a weak supervision approach to detect disinformation with limited
labeled data. We then provide an overview of the chapters in this book that
represent the recent advancements in three related parts: (1) user engagements
in the dissemination of information disorder; (2) techniques on detecting and
mitigating disinformation; and (3) trending issues such as ethics, blockchain,
clickbaits, etc. We hope this book to be a convenient entry point for
researchers, practitioners, and students to understand the problems and
challenges, learn state-of-the-art solutions for their specific needs, and
quickly identify new research problems in their domains.
