I recently read this phenomenal Physics Today article by Takashi Imai and Young Lee, “Do quantum spin liquids exist?” Physics Today 69, 8, 30 (2016). It’s a couple years old, but it’s a clear, relatively non-technical description of quantum spin liquids (QSL) and why they’re interesting along with a easy-to-follow history of developments in the field up to today. This provides some much needed clarity, especially since journal articles about QSL often use varying definitions of QSL.