This book analyses and discusses bonds and bond portfolios. Different yields and duration measures are investigated for negative and positive interest rates. The transition from a single bond to a bond portfolio leads to the equation for the internal rate of return. Its solution is analysed and compared to different approaches proposed in the financial industry. The impact of different yield scenarios on a model bond portfolio is illustrated. Market and credit risk are introduced as independent sources of risk. Different concepts for assessing credit markets are described. Lastly, an overview of the benchmark industry is offered and an introduction to convertible bonds is given.