Purpose of System Definitions

[Josh1980]

I would like to understand the purpose and impact of different system definitions have on my system.

I've fixed and/or broken several builds by messing with this setting, but never understood why.

Can someone enlighten me?

Sorry if this is in the wrong forum

Thanks!

 

[Khaibit]

System definitions refer to actual Mac models - for example, "iMac 18,3" is a mid-2017 iMac with a 27" 5K "Retina" display, a core i7 Kaby Lake CPU, and either a Radeon Pro 575 or Pro 580 GPU. In most cases, ideally you want a definition that is closest to your actual hardware -- macOS uses the system definition to control how it interacts with the hardware in various ways.