Segmentation

In x86 systems, there may actually be 2 address translation steps:

first segmentation
then paging

like this:

(logical) ------------------> (linear) ------------> (physical)
             segmentation                 paging

The major difference between paging and segmentation is that:

paging splits RAM into equal sized chunks called pages
segmentation splits memory into chunks of arbitrary sizes

This is the main advantage of paging, since equal sized chunks make things more manageable by reducing memory fragmentation problems. See also:

stackoverflow.com/questions/16643180/differences-or-similarities-between-segmented-paging-and-paged-segmentation
softwareengineering.stackexchange.com/questions/100047/why-not-segmentation
www.quora.com/What-is-the-difference-between-paging-and-segment-in-memory-management

Paging came after segmentation historically, and largely replaced it for the implementation of virtual memory in modern OSs.

Paging has become so much more popular that support for segmentation was dropped in x86-64 in 64-bit mode, the main mode of operation for new software, where it only exists in compatibility mode, which emulates IA-32.

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