Changing Themes (Look and Feel) in ggplot2 in R

The themes layer is used to style all the non-data ink of the plot, i.e., all the visual elements that are not part of data.

When we create a chart using ggplot2, it automatically uses a default theme. For theming we have a few choices:

1. Use the default theme (What we have seen so far). The default theme is called theme_grey().
2. Use a built-in theme. There are two built-in themes 1) theme_grey() which is default and 2) theme_bw(), a theme with a white background.
3. Modify/override specific elements of the default theme. This is done by using the theme() function. It overrides the graphical parameters of the default theme.
4. Create your own theme