Nature Protocols is an interactive online resource for laboratory protocols, providing step-by-step instructions for using and adapting research techniques that users can take straight to the lab bench and apply in their own research. Protocols are commissioned by the editorial team from leading laboratories. They are edited and peer-reviewed to ensure the highest level of quality and reproducibility. All protocols must have been proven to work, having been used to acquire data in published research papers. The focus is on providing practical information that is not available in research papers, such as explaining the critical points in the procedure, anticipated results (what to expect if the experiment has worked) and how to troubleshoot problems. Nature Protocols publishes protocols used to answer outstanding biological and biomedical research questions, including methods grounded in physics and chemistry that can be applied to biological problems. Protocols are added weekly and cover new methods, as well as classic, wellestablished techniques. Protocols are fully searchable online and also available in print on demand.