Leaving your iPhone or iPad might feel like a convenience, but if you ever leave it unattended, lose it, or have it stolen, it leaves you open to everything from pranks to having all your personal data exposed. By enabling a simple, easy-to enter 4-digit Lock screen passcode, you not only make it much, much harder for someone to get at your data, but you also make it much harder for them to do anything but user it as a paperweight if you ever lose it or have it stolen.
Full story from the iMore Blog...