Today Apple sent out the newest version of iOS to all devices capable of running versions of iOS 8. This update brings iOS to version 8.1.3, and like the 8.1.2 patch before it, this update is aimed at squashing bugs that still remain after the major iOS 8.0 and 8.1 updates from last year. Apple's changelog for the update is below, although there are often small bug fixes that don't get put on the list of changes.
Reduces the amount of storage required to perform a software update
Fixes an issue that prevented some users from entering their Apple ID password for Messages and FaceTime
Addresses an issue that caused Spotlight to stop displaying app results
Fixed an issue which prevented multitasking gestures from working on iPad