OS X (originally Mac OS X)[23] is the line of graphical operating systems developed, marketed, and sold by Apple Inc. which succeeds the original Mac OS, which had been Apple's primary operating system since 1984. Unlike the earlier Macintosh operating system, OS X is a Unix-based operating system[24] built on technology developed at NeXT from the second half of the 1980s until early 1997, when Apple purchased the company.[25]