Ch. 3. 2. Outline. Principles form the basis of methods, techniques, methodologies and toolsSeven important principles that may be used in all phases of software developmentModularity is the cornerstone principle supporting software designCase studies . Ch. 3. 3. Application of principles. Principles apply to process and productPrinciples become practice through methods and techniquesoften methods and techniques are packaged in a methodologymethodologies can be enforced by tools.