What is a flow diagram & flowchart? (7 types + definitions)

This type of diagram is used to map the flow of data or through an information system or process. A DFD would therefore also show all the accompanying inputs, outputs and functions that relate to the capture or use of data as well where the data lives.

Data flow diagrams are perhaps the most specialized of the flow chart/diagram family and actually have their own type of notation and flowchart symbols: Yourdon & Coad and Gane & Sarson. Both duos wrote seminal books that included DFDs, “Structured Design” by the former, “Structured Systems Analysis: Tools and Techniques” by the latter.

Data flow diagrams can be further broken down into Logical DFDs and Physical DFDs. Logical diagrams focus on the business operations in relation to data and information flow, not how the system itself works. They're less technical and therefore easier to understand. Physical DFDs go into a deeper level of details; the who, what and where of data flow.

If the idea is to work smart, not harder, putting together a workflow diagram is something you should consider. These diagrams can be created at the organization level all the way down to charts for a particular service or a single project to chart the flow of decisions, documents, tasks and activities.

Where a user flow diagram optimizes how a user interacts with your product or service, a workflow diagram ensures optimization of your internal processes.

How do you keep track of who does what and when in an interdisciplinary or collaborative project? The difference between a swimlane diagram and the workflow diagram is that each person, group, department, etc. of a process has a clear cut lane. Whichever way you orient the lanes, vertically or horizontally, the point is to see the entire process and the interactions between the various role players as they happen in a neat and easily consumable way.

Think of this as almost an “interaction flowchart”.

Process flow diagrams, or process maps, come to us from the world of mechanical engineering. Specifically from Frank and Lillian Gilbreth, industrial engineers who wrote about the concept all the way back in 1921 in “Process Charts: First Steps in Finding the One Best Way to Do Work”.

As they put it, “the process chart is a device for visualizing a process as a means of improving it. Every detail of a process is more or less affected by every other detail; therefore the entire process must be presented in such form that it can be visualized all at once before any changes are made in any of its subdivisions”.

In other words, a PFD sequentially depicts the steps of a process and its sub-processes and how they relate to one another.

While a process flow diagram, or process flowchart, is still often used in engineering you can use it for any application, in any industry.

EPCs, or event-driven process chains, are flowcharts that are specifically meant for illustrating and modeling business processes as a chain of events and activities that influence each other.

This type of chart also has some of its own unique notation, notably the AND, OR and XOR operators along some of the connectors depending on the process.

SDL diagrams are for detailing the specific behavior of real-time systems, with said system broken down into blocks and processes. Given the name, these diagrams lay out the specifications and states of behaviors throughout a system.

Unified modeling language diagrams, or UMLs, are quite similar to SDLs and illustrate a system and how users interact with it, generally software, from a higher level.

The most common of these are activity diagrams and are used to illustrate the actions in a process.