Complex sentence: NeXTSTEP is a discontinued object-oriented, multitasking operating system based on UNIX, which was developed by NeXT Computer in the late 1980s and early 1990s.
Split into simpler sentences: NeXTSTEP is a discontinued object-oriented, multitasking operating system based on UNIX. It was developed by NeXT Computer in the late 1980s and early 1990s.