In biochemistry, the native state of a protein or nucleic acid is its properly folded and/or assembled form, which is operative and functional.
While all protein molecules begin as simple unbranched chains of amino acids, once completed they assume highly specific three-dimensional shapes.
However, "native state" is used almost exclusively in the singular, typically to distinguish properly folded proteins from denatured or unfolded ones.
Proteins in the native state will have defined secondary structure, which can be detected spectroscopically, by circular dichroism and by nuclear magnetic resonance (NMR).
Nucleic acids attain their native state through base pairing and, to a lesser extent, other interactions such as coaxial stacking.