Nucleophiles, nucleophilicity and relationship between nucleophilicity and basicity

The concept of nucleophilicity and electrophilicity are most useful in understanding polar reactions. Polar reactions proceed by the movement of pairs of electrons from areas of high electron density, called nucleophiles to areas of low electron density called electrophiles or from filled orbitals to empty orbitals. Nucleophiles also control the rate of bimolecular substitution reaction. Certain aspects of this concept, however; not been treated with sufficient clarity. The aim of this write up is to clarify these aspects and to report a comparative study about nucleophilicity and basicity.