The Free On-line Dictionary of Computing (30 December 2018):
Any programming language in which sections of
source code contained within pairs of matching delimiters
such as "" and "" (e.g. in C) or "begin" and "end"
(e.g. Algol) are executed as a single unit. A block of code
may be the body of a subroutine or function, or it may be
controlled by conditional execution (if statement) or
repeated execution (while statement, for statement, etc.).
In all but the most primitive block structured languages a
variable's scope can be limited to the block in which it
Block-structured languages support structured programming
where each block can be written without detailed knowledge of
the inner workings of other blocks, thus allowing a top-down
See also abstract data type, module.