In general, something that is nested is fully contained within something else of the same kind. In programming, nested describes code that performs a particular function and that is contained within code that performs a broader function. One well-known example is the procedure known as the nested do-loop . In data structures, data organizations that are separately identifiable but also part of a larger data organization are said to be nested within the larger organization. A table within a table is a nested table. A list within a list is a nested list.
A common alternative to nested is the prefix sub , as in subprocedure, substructure, subtransaction, and so forth.