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Any programming language in which sections ofsource code contained within pairs of matching delimiterssuch as "" and "" (e.g. in C) or "begin" and "end" (e.g. Algol) are executed as a single unit. A block of codemay be the body of a subroutine or function, or it may becontrolled by conditional execution (if statement) orrepeated execution (while statement, for statement, etc.).In all but the most primitive block structured languages avariable's scope can be limited to the block in which itis declared.Block-structured languages support structured programmingwhere each block can be written without detailed knowledge ofthe inner workings of other blocks, thus allowing a top-downdesign approach.See also abstract data type, module.