Nanodiscs are a type of lipid bilayer nanostructure that is used in biochemical and biophysical research to study membrane proteins and lipid-protein interactions. They are composed of a small patch of lipid bilayer encircled by a belt of amphipathic proteins called scaffold proteins, which stabilize the structure. Nanodiscs provide a stable and uniform environment for membrane proteins, allowing for more accurate and detailed analysis of their structure and function. They are commonly used in studies of drug interactions, membrane protein structure, and lipid-protein interactions.