Tooltips and popovers are used to add additional content, like short notes. They can be useful for short help-documentation. A tooltip is used to embed a short note into a tag; by default they are activated by hovering over the tag. A popover is used to embed a longer note into a tag; by default they are activated by clicking on the tag. A tooltip has only a text title; a popover has a title, which is generally text, and content, which can be HTML.

bs_button("Hover for tooltip") %>%
  bs_embed_tooltip(title = "I'm a tooltip")
bs_button("Click for popover") %>%
  bs_embed_popover(title = "I'm a popover", content = "Really!")

Both of these functions have an additional argument, placement, which defaults to "top", following the Bootstrap default. The possible values are c("top", "bottom", "left", "right", "auto").

bs_button("Another tooltip") %>%
  bs_embed_tooltip(title = "I'm on the right", placement = "right")

Tooltips and popovers are not activted by default in Bootstrap. For either of them to work properly, you will have to activate them on your page, using the use_bs_tooltip() or use_bs_popover() functions. For each page you write, you will need to call each function once, at most.

Reference

For more information, please see the Bootstrap JavaScript page on tooltips or popovers.