The origins of the OS X operating system can be traced back to the
NeXTSTEP OS that was launched by the NeXT company, created by Steve Jobs, which was a multitasking and object oriented operating system.
The NeXTSTEP model was subsequently taken to Apple upon his return to the company and adapted throughout the years. Now, several versions of the OS X exist, with almost yearly updates for the OS X system released for Mac users. These updates bring internal fixes and improvements that are important for the compatibility of the applications on the system.
It is particularly useful for IT professionals to understand the OS X systems and whether the applications they need to use are compatible with the operating system they have in place, particularly if they have to use Apple products for their work.