Is there any difference between I and du?
When would you use I and when would you use du? Tak!
Exactly as Jose said. In English 'you' can be both one person or multiple persons. In Danish there is a difference. 'Du' is you, singular, and 'I' is plural - and yes, that can be confusing, since Danish uses the same verb for every person. Jeg er, du er, I er. But you'll get it soon. And please note that if the I in capital is referring to a person, where as a lovercase i is 'in'. Hope that makes sense (:
One thing to notice is that, when accessed in the laptop-desktop version of Duolingo, there are rather good grammar explanations accompanying many of the lessons (with the characteristic Duolingo bit of style and attitude). And, indeed, the very first lesson in the tree has an explanation of this. I mention this because it took me quite a while to find these (scroll down on the opening page for each lesson). These explanations are very good at paring out the complexities which is good until, well, one needs to begin learning the complexities. At that point I found a good grammar book to be what I needed (I like Grammatikken: Handbag i dansk grammatik for udlændinge). Good luck with Danish!