@flo 1) Good question, I think, though I’m not sure exactly what you’re asking as you seem to have dropped a verb. Guessing with some info, I might offer that some web sites try to guess whether a user is on a mobile device and if so, switch to a version designed for them. Usually it will be layed out differently, and is often determined by the reported display size available to the web browser, as that’s often the main issue.
I just tried loading fluther on a mobile device and got redirected to i.fluther.com, where I infer that i. refers to iPhone, particularly because it looks like absolute trash on my non-iPhone Android device. Or there’s just a bug.
Annoyingly, requesting i.fluther.com on a desktop seems to redirect to www.fluther.com, probably overriding the request based on data my browser reveals to servers.