This review broadly covers soot formation and its oxidation. Several physical and microstructural aspects are present which are linked to theories attempting to explain soot particle nucleation and growth stages. Chemical reaction and nucleation, being extremely rapid, make it difficult to provide a detailed mechanism of formation; however, a number of suggestions are made to explain the reaction path by which a hydrocarbon molecule may increase in size and mass. The nature of the soot nucleus is treated at some length illustrating the evidence to favour the droplet theory in the case of pyrolysis. Correlations regarding particle growth by agglomeration are also presented. Particle oxidation in small flames is discussed together with applicability of a number of soot oxidation equations.