What's the underlying code that Netflix uses to pull off automatically spawning a movie details pop-up when users mouse over a movie poster on their site?

I am putting together a site-wide help system on my website and I'd like to be able to insert 'help' icons such as where needed, which when hovered over would spawn a similar netflix-style movie details window with relevant help information. NOTE: Just as Netflix has figured out a way to do in their movie-details window, I'd very much like to be able to include clickable links in the pop-up window

Any suggestions or links to where I can learn more would be sincerely appreciated! Thanks!