This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book describes leading social scientists from both Europe and the United States to share experiences on Internet survey research and to report and discusses data collection through the Internet. It reviews the state of the art in Internet surveys and provides a snapshot of some climate of Internet survey methodology. The book presents innovative ways researchers have begun to attempt to minimize each of the sources of error in Internet surveys and also discusses potential directions for future research and development. It also provides a theoretical background on mixed-mode designs for online research with an empirical knowledge base on the implications of mixed mode for data integrity, questionnaire design, and analysis. The book describes the methodology to set up a panel that combines the technology of Internet surveys with a “true” longitudinal and probability-based sampling design.