The end of 2020 marks five years of publishing for Ledger, and we are proud to have been able to continue our mission to provide an avenue for high-quality, peer-reviewed blockchain research even during what has been a challenging year for the global community. This year, we published a variety of papers under the broad umbrella of cryptocurrency and blockchain studies: we began with a paper by Chad Albrecht, Steven Hawkins, and Kristopher McKay Duffin that applies the concept of Whole Number Bias to Bitcoin’s fractional denominations; we published a paper by Thomas Harding that introduces a class of retargeting algorithms for proof-of-work blockchains that have the potential to improve responsiveness and stability; next came a paper by Can Ozturan on implementing a distributed, autonomous barter exchange via smart contracts on the Ethereum platform, and a paper by Michael Kuperberg, Daniel Kindler, and Sabina Jeschke on the potential application of blockchain technology to railway control systems; we published a paper by Pericles Philippopoulos, Alessandro Ricottone, and Carlos G. Oliver on a potential system to use proof-of-work hashpower to solve optimization problems for scientists; and we rounded out the year with a paper by Kim P. Huynh, Christopher S. Henry, Gradon Nicholls, and Mitchell W. Nicholson on Bitcoin adoption benchmarking data, adding to our understanding of who owns and uses Bitcoin and why. Over the last five years we are proud to have published dozens of articles—hundreds of pages of free-to-access, peer-reviewed research that have added to the greater understanding of these emerging systems and technologies, and we look forward to delivering more into the hands of researchers in the future. That work should get a little easier, going forward, as this year saw Ledger’s indexing by two major indexes: Clarivate Analytics’s Web of Science, through its Emerging Sources Citation Index, and Elsevier’s Scopus index. These inclusions will expand access to Ledger’s articles and broaden the number of potential authors as we look to 2021 and beyond. As we are every year, we find ourselves deeply grateful that our authors have chosen Ledger as a home for their work. We would like to thank our authors, our tireless volunteer editors, and our distinguished editorial board. Furthermore, our open-access (free to read) and author-fee-free (free to publish) journal would not be possible without our generous supporters: our publisher, the University Library System of the University of Pittsburgh, and our sponsors, the Bitcoin Unlimited Community Organization and the Institute for Cyber Law, Policy, and Security at the University of Pittsburgh. Without their generosity, our work would not be possible. Lastly, we would like to thank you, the readers and researchers for whom this work is done. Without you to provide a demand for well-reasoned and well-reviewed scholarship, we wouldn’t have a reason to provide it. Here’s to another year done and a better one to come. Yours, Christopher E. Wilmer, Co-Managing Editor 1GaKwY1LV8m4HtA9qQnyk9vtrqkW4KY92M