The elastic response of a polymer is uniquely sensitive to its structure and interactions with the solution in which it is bathed. We study the elasticity of single polymers, with an eye towards understanding the solution physics that governs biopolymer activity in vivo. Particularly, we have pioneered the study of polymer elasticity at very low (sub-picoNewton) forces, discovering novel regimes of polymer behavior that have given new insight into the long-standing problem of charged polymer behavior.