Nature Protocols publishes secondary research articles - predominantly Protocols (including Protocol Updates and Protocol Extensions), but also techniques-related Reviews, Perspectives, Correspondences, Matters Arising, Commentaries, and Consensus Statements - all of which are based on published primary research papers. We cover new techniques and technologies, as well as established methods, used in all fields of the biological, chemical and clinical sciences. Articles are commissioned by the editors. Authors are welcome to submit suggestions for articles as Presubmission Enquiries, which may then be formally commissioned by the editors. Each Protocol contains a full list of reagents and equipment, timing information, and step-by-step procedures (instructions for performing the experiment), as well as information on designing and adapting the technique, its advantages and limitations compared to alternatives, troubleshooting, analysing data, and interpreting results. We also encourage authors to submit videos for steps that are technically challenging. Nature Protocols only publishes non-primary articles (such as Protocol, Review and Perspective articles). In contrast to primary articles (that is, research articles), non-primary articles do not include original (previously unpublished) research findings and may only contain minimal re-analyses of published data. See aims and scope for more info.