[flagged]
Every AppKit and Foundation type uses the NS prefix, and will keep doing so for any foreseeable future. New NS types are added to these frameworks each macOS release.
Citation: I was a NeXTSTEP developer.
Objective-C doesn't have namespaces (like C), so people use two-letter prefixes on their types to prevent name clashes. The NS prefix is used by Apple's Foundation and AppKit frameworks, that originated from NeXTSTEP, hence NS.
there, just told you