Hydrogels are a three-dimensional polymer network that absorbs and retains large quantities of fluids in a liquid state. These materials exist naturally or can be made synthetically as well, tailored to suit the application of interest. Hydrogels play an important role in tissue engineering applications, especially as injectable hydrogels and as bioinks in bioprinting applications. These techniques specifically rely on the material being ejected from a large area via a small aperture that results in a shearing force acting on the material that can alter the properties of the biomaterials. The high shear stresses can also damage materials containing cells. Further, the viscoelastic properties of hydrogels play an important role in their biomedical applications, to name a few as viscosupplements for osteoarthritis treatment, dermal fillers, and ophthalmic lubricants. Hence, in the development of novel hydrogels as biomaterials, understanding material behavior under an applied shear stress is critical and aids in design and optimizing the biomaterials. Rheology is the study of how materials flow and deform and describes the relationship between force, deformation, and time. The focus of this chapter is to introduce the basics of rheological analysis and provide a framework that can act as a guide in characterizing a biomaterial using different analytical techniques involved in rheology. This chapter will also discuss the use of rheology as one of the few characterization techniques in the development of a few biomaterials 3D bioprinting.