Simple definition
L3 cache is often shared across CPU cores and helps reduce traffic to system RAM.
Purpose and use
On architectures that provide it, L3 adds another cache level before selected main-memory accesses.
How does it work?
It is often shared by several cores, but organization and relationships with other caches vary.
Example and verification
Review sharing topology and workload contention before comparing capacities.
Points to watch
L3 is not necessarily one cache shared by every server core, especially across multiple chips or domains.
In short
Useful capacity also depends on locality and sharing scope.