Complex sentence: AIX (Advanced Interactive eXecutive) is a series of proprietary operating systems sold by IBM for several of its computer system platforms, based on UNIX System V with 4.3BSD-compatible extensions.
Split into simpler sentences: AIX (Advanced Interactive eXecutive) is a series of proprietary Unix operating systems developed and sold by IBM for several of its computer platforms. AIX is based on UNIX System V with 4.3BSD-compatible extensions.