Different types of investors are interest in different segments of the yield curve. For example, different types of investors invest short-term as opposed to those who invest long-term. The shape of the yield curve for each segment reflects the attitudes of the investors in that sector. Where two sectors meet there will often be a ‘kink’ in the yield curve.
The is explained in our free lectures note and the free lectures that go with them. The lectures are a complete free course for Paper FM and cover everything needed to be able to pass the exam well.