+A **holder** represents an entity or concept that contains, sustains, or defines a relationship for another. It often signifies a framework or a limiting principle, seen in various contexts from the physical world to abstract mathematical [Spaces](/wiki/Spaces). In formal studies, a holder may establish [Bounds](/wiki/Bounds) or measure conditions between elements.
+## See also
+- [Norm](/wiki/Norm)
+- [Metric](/wiki/Metric)
+- [Continuity](/wiki/Continuity)
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