## Software information and conventions

This book is primarily about the R package bookdown, so you need to at least install R and the bookdown package. However, your book does not have to be related to the R language at all. It can use other computing languages (C++, SQL, Python, and so on; see Appendix B), and it can even be totally irrelevant to computing (e.g., you can write a novel, or a collection of poems). The software tools required to build a book are introduced in Appendix A.

The R session information when compiling this book is shown below:

sessionInfo()
## R version 3.6.1 (2019-07-05)
## Platform: x86_64-apple-darwin15.6.0 (64-bit)
## Running under: macOS Catalina 10.15.1
##
## Matrix products: default
##
## locale:
## [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
##
## attached base packages:
## [1] stats     graphics  grDevices utils     datasets
## [6] methods   base
##
## loaded via a namespace (and not attached):
## [1] bookdown_0.15.4  miniUI_0.1.1.1   rmarkdown_1.17.3
## [4] tools_3.6.1      shiny_1.4.0      htmltools_0.4.0
## [7] knitr_1.26.1

We do not add prompts (> and +) to R source code in this book, and we comment out the text output with two hashes ## by default, as you can see from the R session information above. This is for your convenience when you want to copy and run the code (the text output will be ignored since it is commented out). Package names are in bold text (e.g., rmarkdown), and inline code and filenames are formatted in a typewriter font (e.g., knitr::knit('foo.Rmd')). Function names are followed by parentheses (e.g., bookdown::render_book()). The double-colon operator :: means accessing an object from a package.