Turn your R code into packages that others can easily download and use. This practical book shows you how to bundle reusable R functions, sample data, and documentation together by applying the package development philosophy used in the package known as the tidyverse (and beyond). In the process, you'll work with devtools, usethis, roxygen2, and testthat, a set of R packages that automate common development tasks. Ideal for developers and data scientists, this book gets you creating packages ASAP, then shows you how to get progressively better over time. You'll learn to focus on what you want your package to do, rather than thinking about package structure. Learn the key components of an R package, including code, documentation, and tests. Get tips on good style, such as organizing functions into files. Streamline your development process with usethis, devtools, and RStudio. Create high quality packages by combining unit tests and continuous integration on GitHub. Maximize your chances of a positive CRAN submission. Turn your existing documentation into a beautiful and user friendly website with pkgdown.