A block diagram is a diagram of a method in which the principal parts or functions are represented by cubes linked by lines that reveal the connections of the blocks.
The significant cities (functions) are recorded but the small county roads and city streets aren't. After troubleshooting, this large level map is helpful in narrowing down and isolating in which a problem or fault is.
Block diagrams rely on the principle of the black box where the contents are concealed from view either to avoid being distracted by the details 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.
Block diagrams are usually used for higher degree, less comprehensive descriptions that are meant to clarify general theories without issue for the details of implementation. Contrast this with the schematic diagrams and design diagrams used in electrical engineering, which show the implementation information of electric elements and physical construction.
In biology there's an increasing use of technology fundamentals, techniques of research and methods of diagramming. There is a correlation between the block structure and what is named Systems Biology Graphical Notation. As it is there's use made in systems economics of the block diagram technique harnessed by control technology in which the latter itself is a program of management theory.
In electrical engineering, a layout may often start as a quite higher level block structure, getting more and more detailed block diagrams as the design progresses, finally ending in block diagrams detailed enough that each individual block can be readily implemented (at which stage the block diagram is also a schematic diagram). This is known as top down design.  Geometric shapes are frequently used at the diagram to assist interpretation and clarify meaning of this process or version. The geometric shapes are linked by lines to signify association and direction/order of traversal. Each engineering field has their own significance for each form. Block diagrams are employed in every discipline of technology. They're also a valuable source of theory building and educationally beneficial in non-engineering areas.
An example of this is the function block diagram, one of five programming languages found in section 3 of this IEC 61131 (see IEC 61131-3) standard that is quite formalized (see formal method ), with strict rules to how diagrams should be assembled. Directed lines have been utilised to link input variables to block input signal, and block presses to output factors and inputs from other blocks.
For example, a block diagram of a wireless is not anticipated to show each and every link and dial up and switch, but the design diagram is. The schematic diagram of a wireless doesn't show the width of every connection in the circuit board, but the layout diagram will not.
In process control, block diagrams are a visual vocabulary for describing activities in a complex system where cubes are black boxes which represent logical or mathematical operations which take place in sequence from left to right and top to base, although not the physical entities, like chips or radiators, that execute these operations. It is possible to create such cube diagrams and execute their functionality with specialized programmable logic controller (PLC) programming languages.