Explain what is meant by the term structure of interest rates. Critically evaluate the different theories that have been developed to account for the various shapes of the term structure.

It is around an essay question and just need some help on this. If you could at least provide an explanation for each of the theories used for the various shapes, the different shapes of the curve, how the theories explain these shapes and which theory may be best to explain why that shape of the yield curve has occurred, that would be great!

Thank you.