Violin plots allow to visualize the distribution of a numeric variable for one or several groups. It is really close from a boxplot, but allows a deeper understanding of the density. Violins are
particularly adapted when the amount of data is huge and showing individual observations gets impossible. Seaborn is particularly adapted to realize them through its violin function.
Violinplots are a really convenient way to show the data and would probably deserve more attention compared to boxplot that can sometimes hide features of the data. (read more)
Ggplot2 is the best option to build your violin plot. It provides the geom_violin() utility that automatically builds it.
If you want to stick to baseR, the vioplot library will allow you to build your violin plot.