Definition of the "box"

Now, I know this is a very basuc question.I thought I had a pretty good understanding of what the "box" is in football.Except I was watching a video, and now think I may be wrong.

Definitions I have found:

1.Five yards from LOS and tackle to tackle

2.10 yards deep from LOS from tackle to tackle

3.One defensive high school playbook defined the box as "tackle to tackle, 10 yards from LOS and back

So, is the tackle box tackle to tackle, and 10 yards deep?

Or, is the box tackle to tackle, and literally all the way down the field?

Again, I know this is basic but i want to make sure my initial idea of "tackle to tackle, and ten yards deep from LOS" was right.any help would be awesome, thanks.