An assessment of the diversity of phosphazene chemistry is presented w
ith an emphasis on recent developments and their significance. Fundame
ntal properties of phosphazenes are examined such as structure, nomenc
lature and bonding, and the various synthetic procedures are catagoriz
ed. In addition, the more important reactivity patterns are detailed a
nd analysed. The review compares all systems containing the phosphazen
e bond, and makes extensive reference to previous reviews on specific
types of phosphazene.