# Chapter 2 Introduction

You can label chapter and section titles using `{#label}` after them, e.g., we can reference Chapter 2. If you do not manually label them, there will be automatic labels anyway, e.g., Chapter 4.

Figures and tables with captions will be placed in `figure` and `table` environments, respectively.

    par(mar = c(4, 4, .1, .1))
    plot(pressure, type = 'b', pch = 19)

Figure 2.1: Here is a nice figure!

Reference a figure by its code chunk label with the `fig:` prefix, e.g., see Figure 2.1. Similarly, you can reference tables generated from `knitr::kable()`, e.g., see Table 2.1.

    knitr::kable(
      head(iris, 20), caption = 'Here is a nice table!',
      booktabs = TRUE
    )

Table 2.1: Here is a nice table!
Sepal.Length | Sepal.Width | Petal.Length | Petal.Width | Species
--- | --- | --- | --- | ---
5.1 | 3.5 | 1.4 | 0.2 | setosa
4.9 | 3.0 | 1.4 | 0.2 | setosa
4.7 | 3.2 | 1.3 | 0.2 | setosa
4.6 | 3.1 | 1.5 | 0.2 | setosa
5.0 | 3.6 | 1.4 | 0.2 | setosa
5.4 | 3.9 | 1.7 | 0.4 | setosa
4.6 | 3.4 | 1.4 | 0.3 | setosa
5.0 | 3.4 | 1.5 | 0.2 | setosa
4.4 | 2.9 | 1.4 | 0.2 | setosa
4.9 | 3.1 | 1.5 | 0.1 | setosa
5.4 | 3.7 | 1.5 | 0.2 | setosa
4.8 | 3.4 | 1.6 | 0.2 | setosa
4.8 | 3.0 | 1.4 | 0.1 | setosa
4.3 | 3.0 | 1.1 | 0.1 | setosa
5.8 | 4.0 | 1.2 | 0.2 | setosa
5.7 | 4.4 | 1.5 | 0.4 | setosa
5.4 | 3.9 | 1.3 | 0.4 | setosa
5.1 | 3.5 | 1.4 | 0.3 | setosa
5.7 | 3.8 | 1.7 | 0.3 | setosa
5.1 | 3.8 | 1.5 | 0.3 | setosa

You can write citations, too. For example, we are using the bookdown package (Xie 2020) in this sample book, which was built on top of R Markdown and knitr (Xie 2015).

### References

Xie, Yihui. 2015. Dynamic Documents with R and Knitr. 2nd ed. Boca Raton, Florida: Chapman; Hall/CRC. http://yihui.org/knitr/.

Xie, Yihui. 2020. Bookdown: Authoring Books and Technical Documents with R Markdown. https://CRAN.R-project.org/package=bookdown.