Mac OS X 10.3 "Panther" was the fourth major release of Apple's desktop operating system, featuring updates to the Finder, Exposé, Safari browser, and including new applications like Font Book and improved security and productivity features. Panther added support for newer PowerPC processors and required a New World ROM for certain older machines. The operating system also included updates to existing applications, improved developer tools, support for newer file systems and network protocols, and a revamped Activity Monitor and Disk Utility applications.