The fundamental aspects of ligand/biomolecule interaction are controlled by thermodynamics and kinetics of the process, in which one tries to obtain knowledge about not only various thermodynamic state functions, but also the important kinetic parameters of association and dissociation rates as well as the activation barriers of such molecular interactions. The ligand binding to biomolecule is a dynamic process which involve steps of ligand binding from its fully solvated state in bulk to a binding site within the biomolecule and then its subsequent un-binding – a process which passes through various transition states crossing different activation barriers on a complex free-energy landscape. Therefore, along with thermodynamics, the kinetics of such process can provide vital information of the rate determining steps. However, obtaining the accurate knowledge of such rates is not trivial. In this talk, I will showcase how Fluorescence Correlation Spectroscopy, together with well-tempered metadynamics simulation, can provide accurate information of the rates of ligand binding/unbinding with G-quadruplex DNA in solution, and how such rates get modulated in crowded molecular environment. A direct correlation of simulation and FCS experimental results further enhances our knowledge of the activation barriers involved in the rate-limiting steps of such ligand/DNA interactions.