This article discusses methods and techniques, procedures and tools that have been found to be necessary or useful in Internet-based experimenting. While the focus is on experiments, many of the methods apply to other types of Internet-based research as well. The article is structured in a step-by-step fashion, guiding the reader through the various stages of setting up and conducting a web experiment. Apart from general issues, the relevant steps begin with planning, generating, and pre-testing an experiment. They continue with recruitment and monitoring, then analysis and archiving.