Nanoclusters potentially have many areas of application as they have unique optical, electrical, magnetic and reactivity properties. Nanoclusters are biocompatible, ultrasmall, and exhibit bright emission, hence promising candidates for fluorescence bio imaging or cellular labeling. Nanoclusters along with fluorophores are widely used for staining cells for study both in vitro and in vivo. Furthermore, nanoclusters can be used for sensing and detection applications. They are able to detect copper and mercury ions in an aqueous solution based on fluorescence quenching. Also many small molecules, biological entities such as biomolecules, proteins, DNA, and RNA can be detected using nanoclusters. The unique reactivity properties and the ability to control the size and number of atoms in nanoclusters have proven to be a valuable method for increasing activity and tuning the selectivity in a catalytic process. Also since nanoparticles are magnetic materials and can be embedded in glass these nanoclusters can be used in optical data storage that can be used for many years without any loss of data.