Cell membranes are believed to be laterally ordered into micro and nano-domains comprising of more fluid liquid-disordered (Ld) and more viscous liquid-ordered (Lo) phases. The latter subphases contain high concentrations of cholesterol and glycosphingolipids. These so call lipid rafts are experimentally distinguishable on the basis of their resistance to detergent solubilisation and are believed to play important roles in membrane function including in protein trafficking and signalling as they can drive protein-protein interactions through sequestering of proteins to these domains. Membrane domains in living cells are difficult to interrogate as they are dynamic and at sub-microscopic length scales they are outside the range of most conventional microscopies. However, they can potentially be imaged using recently developed super-resolution methods and as they are dynamic structures their diffusion can be measured using correlation methods. Therefore, new fluorescent probes are needed that can (a) partition selectively to membranous regions, (b) target the Lo and Ld phases selectively (c) that have appropriate photophysical properties compatible with the above techniques. These include large Stokes shift, high selectivity, excellent photostability, high molecular brightness, low cytotoxicity and high quantum yields. A key aim of this thesis was to design and synthesize new fluorescent probes that sequester specifically to lipid rich regions of cells or models and can distinguish Lo/Ld regions or lipid droplets, using confocal microscopy, fluorescence correlation spectroscopy (FCS), fluorescent lifetime imaging (FLIM) and the relatively new technique of super resolution microscopy, specifically, STimulated Emission Depletion (STED) microscopy.