Your Apple ID can be used for iCloud, iTunes, and the App Store, but if you forget your password, you'll need to reset it!
Updated March, 2017: Rewrote all steps for clarity and removed steps for resetting your password using two-step authentication, which is an older security feature that Apple no longer supports.
Whether you want to log into iCloud on a new device or download something from iTunes or the App Store, you'll need your Apple ID password to get it done. If you can't remember your password, you can reset it using the web browser on your iPhone, iPad, or Mac. If you don't even remember your Apple ID, you can try to recover that too!
How to reset your Apple or iCloud password with your email address or security questions How to reset your password if you have two-factor authentication enabled How to find out your Apple ID if you've forgotten it