The fundamental properties of the RNA double helix—high structural stability and strict base-pairing specificity—have profoundly influenced biological systems throughout evolutionary history and up to today. While the stability allows helices to serve as rigid scaffolds within structured RNAs, it also creates significant energetic barriers to rearrangement, necessitating RNA helicases as chaperones in RNA folding and remodeling. At the same time, the high specificity of Watson-Crick base pairing enables RNA-guided mechanisms, exemplified by CRISPR-Cas enzymes that leverage this specificity for DNA targeting. This talk will explore how these core biophysical properties have shaped RNA’s biological roles, driven evolution of protein families, and enabled modern genome-editing tools.