Conformational dynamics of DNA plays an important role in the life cycle of a cell. Processes like formation of hairpins, local opening of bubbles ("breathing modes"), and coil shape changes are involved in relieving the stresses within the DNA molecule, and in protein navigation around the DNA. Classical experimental methods (UV-absorption, light scattering, NMR) have only a limited ability to study the kinetics of these processes. 

     Recent advances in optical techniques (fluorescence correlation spectroscopy), fluorophore, and DNA chemistry allow us to measure the dynamics of different modes of DNA fluctuations. Three model systems are studied: 1) The fluctuations of small DNA hairpins between the folded and unfolded states, 2) The "breathing modes" within a short A-T rich double-helical region, and 3) Polymer-like conformational fluctuations of long DNA molecules.