Basic line density curve

A density plot is a representation of the distribution of a numeric variable. It is a smoothed version of the histogram and is used in the same kind of situation.
Here is a basic example of a density plot.

# Libraries
library(ggplot2)

# Dataset
set.seed(14012021)
x <- rnorm(200, mean=4)
df <- data.frame(x)

# Density curve in ggplot2
p <- ggplot(df, aes(x=x)) +
  geom_density()
p