To make an analogy to the map making world, a block structure is comparable to a highway map of an entire nation. The major cities (serves ) are listed but the minor county roads and city roads aren't. When troubleshooting, this large level map is helpful in narrowing down and isolating in which a problem or fault is.
A block diagram is a diagram of a system in which the principal components or functions are represented by blocks linked by lines which reveal the connections of the cubes. They are greatly utilized in engineering in hardware design, digital design, software design, and process flow diagrams.
Block diagrams rely on the principle of the black box in which the contents are concealed from view to avoid being distracted by the facts or because the details are not known. We understand what goes in, we know what goes out, but we can't see how the box does its work.
As an example, a block diagram of a wireless is not expected to demonstrate each and every link and dial up and change, but the design diagram is. The design of a radio does not show the diameter of every connection from the printed circuit board, however the layout diagram does.
In electrical engineering, a design may often start as a quite higher level block diagram, becoming increasingly more detailed block diagrams because the design progresses, eventually finishing in block diagrams comprehensive enough that every individual block is readily implemented (at that stage the block structure can be also a schematic diagram). This is known as top down style.  Geometric shapes are frequently utilised from the diagram to aid interpretation and clarify meaning of the procedure or version. Each engineering field has their own significance for each shape. Block diagrams are used in every discipline of engineering. They're also a valuable source of theory building and educationally valuable in non-engineering areas.
In biology there is an increasing use of engineering fundamentals, techniques of analysis and ways of diagramming. There's some similarity between the block diagram and what's called Systems Biology Graphical Notation. As it is there's use created in systems biology of the cube diagram technique harnessed by control technology in which the latter itself is a program of control theory.
Block diagrams are typically used for higher level, less comprehensive descriptions which are intended to describe general theories without consideration for the specifics of implementation. Compare this with the design diagrams and layout diagrams used in electric engineering, which show the implementation details of electric parts and physical construction.
A good example of this is that the function block diagram, among five programming languages defined in section 3 of the IEC 61131 (see IEC 61131-3) standard that's highly formalized (see formal method ), with stringent rules to the diagrams are to be assembled. Directed lines are utilized to link input variables to block inputs, and block outputs to output variables and inputs of different cubes.
In process management, block diagrams are a visual vocabulary for describing actions within a complex system in which cubes are black boxes which represent logical or mathematical operations which exist in sequence from left to right and top to bottom, but not the physical things, like processors or relays, that execute those operations. It's likely to make such cube diagrams and execute their functionality with technical programmable logic controller (PLC) programming languages.