The Debate Between Double and Single Spacing

So, you're typing along, and you get to the end of a sentence. You finish up with a . or a !, ?, or "
And then you hit the space bar before continuing to the next sentence.
But do you hit the space bar once or twice?
I learned to hit the space bar twice, and that's what I've been doing for years.

I heard a while ago that publishers, for example, don't like single spacing. But it's easy enough to use the replace function to swap double and single spaces, so I stored it in my mind, and didn't really do anything about it.

But last month I heard that things are changing more to single spacing. The double spacing came from type writers. But computers automatically add enough space after a sentence that you only have to push the space bar once.
This bit of info intrigued me, so I did a bit of digging. Apparently there's huge debate about whether to single or double space.

But since the industry I'm interested in goes for single spacing, that's what I'll try to do.
I'm training myself to single space my sentences. I think it's finally starting to sink in.