Protein corona is a research concept describing the dynamic layer of proteins that spontaneously adsorbs onto the surface of materials, particularly nanoparticles, upon contact with biological fluids. This academic concept investigates the composition, formation kinetics, and biological consequences of this protein layer, which fundamentally alters the material's biological identity, influencing its fate, cellular interactions, and therapeutic or toxicological profile. Its significance lies in understanding how material properties and the biological milieu jointly determine this corona's characteristics and subsequent biological responses.