Let's talk about the em dash. It's certainly popular. And for good reasons too.
It can be used as an afterthought—sort of like right here.
Often, it replaces parenthesis—if you are looking for something more abrupt—and as a result brings more attention to your intervening thought.
Use it with your "for examples" and you won't regret it—for example, it creates a more formal tone and separates your first clause from your example.
Or use it with "that is" and "namely"—that is, if you want to look professional.
In dialogue, it can often "express a sudden—a quick—change in thought."
Or it can "demonstrate an interruption—"
"An interruption, did you say?"
Useful—the best word to describe the em dash.
Don't confuse the em dash with the en dash! The en dash is shorter and is used for very different purposes. But more on that later.