Flowchart

A flowchart is a diagram that represents a workflow or a process. It can also be defined as a diagrammatic representation of an algorithm. An algorithm is a step-by-step approach used to solve a specific task.

By using different shapes, a flowchart visualizes a solution model for a given problem. These diagrams are helpful for analyzing, designing, documenting, or managing processes. They are used in many different fields, including software engineering and business management. Using a flowchart helps people notice flaws or bottlenecks in a system. A bottleneck is a point where a process slows down or gets stuck.

To understand how a flowchart works, you must look at its symbols and connections. The diagram uses various boxes to represent different types of actions.

These boxes are connected by arrows called flowlines. The flowlines show the order of operations. Most flowcharts follow a standard direction, flowing from top to bottom or left to right.

A terminal symbol, shaped like an oval or a rounded rectangle, marks the beginning or the end of a process.

A rectangular box represents a process step, which is an activity that changes the value, form, or location of data.

A diamond shape represents a decision, which is a conditional operation. This is usually a yes/no or true/false question that determines which path the process takes next.

A rhomboid shape indicates input or output, which is the process of receiving or sending data.

An annotation is an open rectangle used to add extra information about a specific step.

Flowcharts can be organized into different types based on their purpose. Some are called cross-functional flowcharts. These are divided into vertical or horizontal parts to show different organizational units. This allows the author to show exactly which group is responsible for a specific action or decision.

Other researchers have identified different classifications. In 1978, Andrew Veronis named system, general, and detailed flowcharts. Marilyn Bohl also identified system and program flowcharts in the same year. In 2001, Mark A. Fryman identified even more types, such as logic, product, and process flowcharts. Alan B. Sterneckert suggested four general types in 2003: document, data, system, and program flowcharts. Each of these focuses on a specific kind of control within a system.

The history of process documentation began in the early 20th century. In 1921, Frank and Lillian Gilbreth introduced the "flow process chart." They presented this work to the American Society of Mechanical Engineers (ASME). Their tools became a staple in industrial engineering education. In the early 1930s, Allan H. Mogensen began training business people in these tools at conferences in New York. His student, Art Spinanger, later used these methods at Procter and Gamble in 1944. Another graduate, Ben S. Graham, developed the multi-flow process chart to show relationships between multiple documents. In 1947, the ASME adopted a standard set of symbols based on the Gilbreths' original work.

Flowcharts also played a massive role in the birth of computer science. In 1949, Douglas Hartree explained that Herman Goldstine and John von Neumann used flowcharts to plan computer programs. These early diagrams helped programmers organize the logic of electronic computing instruments. As technology changed in the 1970s, the popularity of flowcharts for programming decreased. This happened because interactive computer terminals and third-generation programming languages became common. These new languages allowed programmers to write algorithms more concisely as source code. Many programmers began using pseudo-code instead. However, flowcharts were still used to describe algorithms well into the early 21st century.

There are many specialized symbols used to add detail to complex diagrams.

A cylinder shape represents a data file or a database.

A rectangle with a wavy base represents a single document.

A stack of these rectangles represents multiple documents.

A trapezoid can represent a manual operation that requires human adjustment.

Today, people use many different tools to create these diagrams. Some use simple drawing programs, while others use specialized software. Some software can even create flowcharts automatically from programming languages. These tools help make the complex logic of modern technology easier to see and manage.

Flowcharts connect to many advanced scientific and mathematical concepts. The underlying structure of a flowchart is known as a flow graph. This graph abstracts away the specific contents of the nodes to focus on the connections. There are also newer versions like the Nassi-Shneiderman diagram and Drakon-charts. In modern computing, there are even reversible flowcharts. These focus on the idea of reversibility in computational processes. While most traditional computing steps are irreversible, reversible flowcharts ensure that any step can be undone. This concept provides a theoretical foundation for energy-efficient and structured reversible programming.