Editing Data model (section)

=== Data-flow diagram ===
{{Main|Data-flow diagram}}
[[File:Data Flow Diagram Example.jpg|thumb|240px|Data-Flow Diagram example<ref>John Azzolini (2000). [http://ses.gsfc.nasa.gov/ses_data_2000/000712_Azzolini.ppt Introduction to Systems Engineering Practices]. July 2000.</ref>]]
 
A data-flow diagram (DFD) is a graphical representation of the "flow" of data through an [[information system]]. It differs from the [[flowchart]] as it shows the ''data'' flow instead of the ''control'' flow of the program. A data-flow diagram can also be used for the [[Data visualization|visualization]] of [[data processing]] (structured design). Data-flow diagrams were invented by [[Larry Constantine]], the original developer of structured design,<ref>W. Stevens, G. Myers, L. Constantine, "Structured Design", IBM Systems Journal, 13 (2), 115–139, 1974.</ref> based on Martin and Estrin's "data-flow graph" model of computation.

It is common practice to draw a [[System context diagram|context-level data-flow diagram]] first which shows the interaction between the system and outside entities. The '''DFD''' is designed to show how a system is divided into smaller portions and to highlight the flow of data between those parts. This context-level data-flow diagram is then "exploded" to show more detail of the system being modeled