Hello, I hope this isn't the wrong place for this kind of trivial question (I'm more like an interested enduser at ghe moment):

Let's take peerpad.net as an example. 
If I use it to create a document, on which node is it saved? On my node? (What if I don't have any? You can reach pearpad without having ipfs installed so this confuses me. Or is peerpad.net a relay like ipfs.io/ipfs/? But than what is the hash of the "real" peerpad.net ?). If my friend also edits the document, is he also hosting it?

This isn't a peerpad specific question. Same for orbit. Am I saving my own messages? Or is everyone who is using it saving the whole channel he writes on?