This paper provides a systematic review of the empirical literature on cryptocurrencies, focusing on key topics such as pricing bubbles, regulation, cybercriminality, diversification, and market efficiency. Cryptocurrencies, such as Bitcoin, have experienced significant price appreciation since their inception in 2009, but they face challenges related to regulatory oversight, potential for illicit use, and cybercriminality. The paper identifies the "asset class trilemma" that cryptocurrencies face, which involves the conflict between regulatory oversight, the potential for illicit use, and the risk of cybercriminality. The paper also discusses the growth of cryptocurrency markets, highlighting the diversification benefits and market efficiency of cryptocurrencies. It notes that cryptocurrencies have unique issues such as sustainability, market correlations, and the "curious Kodak case." The paper concludes that cryptocurrencies have the potential to be a credible investment asset class but require further research to address the challenges and opportunities they present. The paper also highlights the need for a systematic analysis of cryptocurrency research to identify gaps in the literature and provide recommendations for future research. The paper is structured into five sections, with the first section introducing the topic, the second section discussing the evolution of cryptocurrencies and the asset class trilemma, the third section discussing the development of cryptocurrency markets, the fourth section investigating unique issues related to cryptocurrencies, and the fifth section concluding the paper. The paper includes a detailed analysis of the literature, with a focus on the key characteristics of the included research and the findings of the studies. The paper also discusses the potential for cryptocurrencies to serve as a hedge against uncertainty and the need for further research to address the challenges and opportunities they present.This paper provides a systematic review of the empirical literature on cryptocurrencies, focusing on key topics such as pricing bubbles, regulation, cybercriminality, diversification, and market efficiency. Cryptocurrencies, such as Bitcoin, have experienced significant price appreciation since their inception in 2009, but they face challenges related to regulatory oversight, potential for illicit use, and cybercriminality. The paper identifies the "asset class trilemma" that cryptocurrencies face, which involves the conflict between regulatory oversight, the potential for illicit use, and the risk of cybercriminality. The paper also discusses the growth of cryptocurrency markets, highlighting the diversification benefits and market efficiency of cryptocurrencies. It notes that cryptocurrencies have unique issues such as sustainability, market correlations, and the "curious Kodak case." The paper concludes that cryptocurrencies have the potential to be a credible investment asset class but require further research to address the challenges and opportunities they present. The paper also highlights the need for a systematic analysis of cryptocurrency research to identify gaps in the literature and provide recommendations for future research. The paper is structured into five sections, with the first section introducing the topic, the second section discussing the evolution of cryptocurrencies and the asset class trilemma, the third section discussing the development of cryptocurrency markets, the fourth section investigating unique issues related to cryptocurrencies, and the fifth section concluding the paper. The paper includes a detailed analysis of the literature, with a focus on the key characteristics of the included research and the findings of the studies. The paper also discusses the potential for cryptocurrencies to serve as a hedge against uncertainty and the need for further research to address the challenges and opportunities they present.