Reproducible sharing: while nbviewer allows the sharing of static narratives, with the release of Binder, originally prototyped by Jeremy Freeman and Andrew Osheroff in late 2015, it became possible to share a live, executable version of one or more notebooks with similar ease. Binder turns a repository of notebooks with explicitly declared dependencies into a live, ephemeral container in the cloud that can be accessed with a web browser and where the user can immediately execute all the code for free without having to download or install any of the underlying software.