Along with updates for iOS, OS X, and watchOS 2, Apple today released a new version of iTunes, iTunes 12.3.1. The update is a minor one, with the release notes only saying it improves overall stability and performance. The iTunes update can be downloaded from the software update function in the Mac App Store. iTunes 12.3.1 comes just over a month after the release of iTunes 12.3, which brought support for iOS 9 and OS X El Capitan. iTunes 12, which brought a major redesign to the iTunes software, was initially released in 2014 alongside OS X Yosemite.
