Today, scientists are exploring the possibility of using nanoscale fluorescent carbon dots instead of luminescent nanosized semiconductor crystals (quantum dots) and rare earth elements nanophosphors. Typically, carbon dots are not made only of carbon, but also contain other elements, including hydrogen, oxygen and nitrogen. Fluorescent sites of carbon dots are usually organic molecules bound by intermolecular or covalent forces. Therefore, these nanostructures should, more precisely, be called organic dots, or luminescent organic clusters. Organic dots possess the attractive properties of low toxicity, being environmentally friendly, offering simple synthetic routes and low cost, as well as having comparable optical properties to traditional quantum dots and organic dyes.