Segmentation divides a program's memory into variable-sized units. What is the primary basis used to determine these segment boundaries?

Segmentation is a memory management scheme that mirrors the logical structure of a program as understood by the programmer or compiler, dividing memory into variable-sized segments corresponding to meaningful logical units — such as a code segment, a stack segment, a heap segment, or segments for individual arrays/functions/objects. This contrasts sharply with paging, where memory is divided into fixed-size physical chunks (pages/frames) chosen purely for implementation convenience and bearing no relationship to a program's logical structure.