Open activity from URL, then use that URL in activity

Question

I basically want the user to click a URL(inside the browser or the email client) and this action to launch an activity(app). From what I've read, it can be accomplished using intent filters. I also need that URL to be used inside my activity, as it is unique for every user who uses the app. I'm not sure how this last part can be done, so I'd appreciate any help. Thank you.