You can do a lot of cool things in R Markdown like bold and italic text.
ggplot(data=iris,mapping=aes(x=Sepal.Width,y=Sepal.Length,color=Species))+
geom_point()+
labs(title="Measurements for Different Species of Iris",
subtitle="Virginica has the longest sepals",
x="Sepal.Width",
y="Sepal.Lenght",
caption="Fisher (1936)")
x<-1234567890
The variable x has a value of 1,234,567,890