The core theme of the previous chapters is that a methodical and structured approach to PT is rather necessary right from the early phases of the development cycle. This will ensure predictability and controllability of application performance in practice. The preparatory activities associated with PT (Figure 4.1) are of great importance and are distributed over the life cycle phases of requirement elicitation and analysis, High Level Design (HLD), Detail Level Design (DLD), and several sets of system builds. These activities help define and provide continuity between the high level requirements for application performance, strategies for testing, a framework for designing the tests (see Barber, 2004), and artifacts used to plan and carry out tests. This chapter contains a detailed consideration of the definition phase while Chapters 5 and 6 highlight issues related to the design and build phases associated with the preparatory activities as shown in Figure 4.1.