Defects are most detrimental entities which deter the smooth operation and deployment of the software system and can arise in any part of the life cycle, they are most feared, but still Defect Prevention is mostly discounted field of software quality. Unattended defects cause a lot of rework and waste of effort. Hence only finding the defects is not important, finding the root cause of the defect is also important which is quite difficult due to levels of abstraction in terms of people, process, complexity, environment and other factors. Through this study various techniques of Defect classification, prevention and root cause analysis are analysed. The intent of this paper is to demonstrate the structured process showing defect prevention flow and inferring three T's (Tracking, Technique and Training) after analysis.