(a) Upon binding to its target, the fluorescently labeled small molecule drug presents an increase in anisotropy. (b) Titration and measurements of fluorescence anisotropy, enable accurate reconstruction of binding isotherms. (c) Standard optical arrangement for measurements of fluorescence anisotropy. The subscript letters V and H, stand for vertical and horizontal. The first subscript, indicates the direction of polarization of the excitation light. The second subscript, indicates the direction of polarization of the emission polarizer. Adapted with permission from [255], Nature Publishing Group.