Transaction logs capture the interactions between online information retrieval systems and the users. Given the nature of the Web and Web users, transaction logs appear to be a reasonable and relevant method to collect and investigate information searching behaviors from a large number of Web users. Based on a series of research studies that analyzed Naver transaction logs, this study examines how transaction log analysis can be applied and contributed to the field of web searching and suggests future implications for the web searching field. It is expected that this study could contribute to the development and implementation of more effective Web search systems and services.