Wet, soft, squishy, and tunable: Hydrogels are highly cross-linked polymer networks that are heavily swollen with water. Hydrogels have been used as dynamic, tunable, degradable materials for growing cells and tissues. Zhang and Khademhosseini review the advances in making hydrogels with improved mechanical strength and greater flexibility for use in a wide range of applications. Science , this issue p. eaaf3627

Bioprinting is an emerging technology with various applications in making functional tissue constructs to replace injured or diseased tissues. In all bioprinting strategies, the bioinks are an essential component. We provide an in-depth discussion of the different bioinks currently employed for bioprinting, and outline some future perspectives in their further development.