Structural studies of replicative helicases have provided a detailed view of how these molecular motors coordinate DNA unwinding with the progression of the replication fork. High-resolution cryo-EM and crystallographic analyses reveal that replicative helicases form ring-shaped assemblies that encircle single-stranded DNA, using sequential ATP binding and hydrolysis events to drive conformational changes that propel the enzyme forward. These coordinated structural transitions generate a rotary or inchworm-like movement that separates the duplex with high speed and processivity. Interactions with polymerases, primases, and other replisome components further refine helicase dynamics, ensuring that unwinding is tightly synchronized with leading- and lagging-strand synthesis. Together, these structural insights illuminate the mechanistic basis of genome duplication fidelity and are informing the development of inhibitors that target helicase function in pathogens and cancer cells.