SETI in 2021

In this second installment of SETI in 20xx, we very briefly and subjectively review developments in SETI in 2021. Our primary focus is 93 papers and books published or made public in 2021, which we sort into six broad categories: results from actual searches, new search methods and instrumentation, target and frequency selection, the development of technosignatures, theory of ETIs, and social aspects of SETI.