Why is Y! constantly emailing me that my Instagram password has changed?

What the Heck is Instagram anyhow? If you can't load from your pc to this picture source (I'm assuming that's what it is, like Flickr and Photobucket) why would you even want it? I do not have a cell phone or any of those other wifi toys, so how did an Instagram get set up in association with my Y! email. I keep getting notices that the password has been changed (three times just today). (Does this mean they gave a fake email (which just happened to be mine), or has someone hacked my Y! account? (I'd ask Y! but they seem to "run" on "autopilot." Click feedback and you just get taken to some Gravatar idiotic chat trainwreck that no one reads.)