"Less is more " is perhaps the suitable saying that springs to mind when we talk about this design principle, Ockham's Razor. When two products that perform the same functions but one is designed in a complicated way and the other one is less it , people tend to choose the simplest one . The statement of Ockham’s you

Redundancy is a design principle  whereby elements are used more than necessary to prevent system failure, to increase the performance or maximize the functionality. There are four types of redundancy being used ; which are  diverse redundancy , homogeneous redundancy, active redundancy and passive redundancy . Diverse redundancy is the use of multiple elements of different types to perform the same function (for example,

Flexibility-Usability Trade off As the flexibility of system increase, the usability decrease.  For example, on Figure 8.3.1, the it shows a screw driver that has nay types of sizes and tip of screw driver. However it has flexibility-usability trade off because it is less efficient. Figure 8.3.1: multi tip of screw driver The screw driver like on Figure