Proteins possess inherent flexibility, which is determined by their structures and is essential for carrying out their biological functions. The magnitude of movement is related to the specific functional requirements proteins need to fulfill. The regions of plasticity or rigidity within a protein fold, as well as the degree of conformational flexibility during binding and functional processes, primarily depend on electrostatic and hydrophobic properties or their compensatory interactions. 101 Therefore, proteins have inherently enriched molecular dynamics which can be crucial for their functionality and stability. The protein molecules undergo a variety of structural transitions at timescales such as the fast (ps-ns) as well as the intermediate and slow (µs -s) timescale, as illustrated in Figure . These dynamics display physical motions ranging from global rearrangement and collective domain movement (>µs), 102 loop motion and gating (ns-ms), backbone fluctuation or rotation diffusion/molecular tumbling (ns), 105 side-chain rotations (ps-ns), 106, 107 and bond vibrations (fs-ps), 108 are relevant to protein functionality, 109 and also stability in solution and solid state after drying. As shown in Figure , proteins interact with water molecules while the excipient is preferentially excluded from the protein surface, and the formation of hydrogen bonds between water and protein contributes significantly to the protein stability in the aqueous solution. After lyophilization, the removal of water largely slows down the global motion, which makes the local motion a primary component that may modulate the protein dynamics and therefore stability at the temperature below the glass transition temperature (Tg). Therefore, it is crucial to understand how the excipients or drying processes impact the protein dynamic, such as global or local motions, in the solid state and potential correlation with storage stability.