Red Hat Linux 9 was released in 2003 and featured the Bluecurve interface for easy navigation, support for Native POSIX Threads for improved performance, and included OpenOffice.org, Mozilla, and email/calendar clients. Red Hat Enterprise Linux 5, released in 2007, was based on the Linux 2.6.18 kernel and included over 1200 components along with virtualization support, optimizations for multi-core CPUs, and enhanced security features such as SELinux.