RTVS is an add-in for Microsoft Visual Studio, which adds R language development capabilities to the popular Windows-based IDE. If you don't already have Visual Studio, you can download Visual Studio Community for free. Then, download and install RTVS to add the "R Tools" menu to Visual Studio.
To get started with R in Visual Studio, just create a new project and choose the "R" template. To interact with R directly, you can type commands directly to the R command line while recalling and editing previous commands. Intellisense tab-completion makes it easy to find and type commands, and get quick access to R documentation. R objects you create appear in the Variable Explorer window, and charts appear in the R Plot window. You can create and edit R scripts using a syntax-aware folding editor, and set breakpoints and step into running code with the R code debugger. Once your R script or RMarkdown document is working, you can check it into Git or GitHub. And because you're working within the Visual Studio environment you have access to all of its standard features as well, including the ability to simultaneously edit code in Python, C++, or any other supported language, use any Visual Studio Extension, and have complete control over appearance, window placement, and key bindings (even Vim!).
This preview release is just the beginning: we have plenty of plans to extend RTVS further. Requests from our private preview include support for creating R packages within RTVS, and support for non-Windows platforms. (This release requires the Windows-based Visual Studio, and doesn't support the cross-platform Visual Studio Code IDE.) If you have preferences or suggestions for features we can add, please take the RTVS Survey, or submit an issue (or even a pull request!) to the RTVS Github repository. (RTVS is released under the MIT open-source license.) And if you encounter any issues with the preview release (or just want to send comments), you can provide a "smile" or "frown" via the Feedback menu in the R Tools menu.
If you'd like to check out a tour of RTVS in action, RTVS's product manager John Lam presents this lap around the features.
Get started with R Tools for Visual Studio here, or for more information check out the official blog post by Shahrokh Mortavazi linked below.
Microsoft Machine Learning Blog: R Tools for Visual Studio Announced