Some books on Software Testing give superficial accounts of testing techniques. In particular, the concepts of equivalence class, boundary testing, and orthogonality matrices are described in vague ways, with the apparent assumption that the meanings of the names are sufficient to explain the details of the test procedure.

The motivation for the test design strategies is simple: there are too many combinations of possible program flows or variables to test completely. Methods are required to reduce the testing load with a minimum sacrifice of coverage. Instead of testing all variables, focus on the ones near the boundaries of the permitted range of possibilities; or, only test one member of an equivalence class. These are important strategic approaches to test design simplification that should be understood in sufficient detail to know how to use them properly.