Have you ever stopped to think about how much sensitive information lives on your iPhone? From passwords and financial details to personal reflections and work notes, your device is a treasure trove ...

This week a reader writes, "In [a recen] column you mentioned that you keep some of your passwords in your iPhone in a locked note. Could you please explain how one locks a note? It sounds so useful.

There's a lot you can do on your iPhone, even without relying on third-party apps from the marketplace. You can have RCS-enabled conversations on iMessage, or video ...