This book describes the stages of online purchase and consumer behavior. Consumer have their own motives in doing online transaction. This transaction is in form of buying and purchasing. One place to do it is e-commerce site. Each consumer has experience after doing transaction. Their experience determine satisfaction and as a basis for future decision making. This research goal is to know stages of consumer purchase and how consumer behave while doing transaction online. Research method is qualitative descriptive method and use consumer who done transaction online as sample. The research result are consistent with Philip Kotler and Gary Amstrong (2006). Researcher find that consumer tend to have Dissonance Reducing Buying Behavior.