Complex sentence: Linux (pronounced or, less frequently,) is a Unix-like computer operating system kernel assembled under the model of free and open-source software development and distribution an first released on September 17,1991 by Linus Torvalds.
Split into simpler sentences: Linux (pronounced or, less frequently,) is a Unix-like computer operating system assembled under the model of free and open-source software development and distribution. The defining component of Linux is the Linux kernel, an operating system kernel first released on September 17,1991 by Linus Torvalds.