A pie chart is a type of diagram that displays ratios.

Diagrams are useful tools in the workplace and educational settings. They aid users in project planning, problem solving and creative thinking. Different styles of diagrams, such as graph or chart diagrams, can add value to a project or idea and help others better absorb and remember the ideas presented. On the other hand, some diagrams hinder presentation instead of helping.

## Pictorial

Pictorial diagrams display a fairly accurate image of an object, usually with explanatory text. Some pictorial diagrams may simply be an actual-sized photo while other diagrams increase the size (but tend to keep the image to scale) of the image to show smaller, sometimes microscopic components.

Many doctor’s offices display pictorial diagrams of different parts of human anatomy, with labels pointing to specific body parts, systems and important features. Pictorial diagrams can also explain the inner parts and how a piece of machinery works or the biology of a plant.

## Relationship

Relationship diagrams “aim to represent the structural or organizational features of a situation through combinations of words, lines and arrows, and a wide selection of boxes, blobs and circles,” explains the U.K.’s Open University. These diagrams can depict “cause and effect” or correlation relationships.

A flow chart presents dynamic or situational relationships between different processes. The shapes in each process indicate actions (automatic or manual), decisions, data output and preparations, among other things. A decision tree is a similar diagram that describes decisions you can make in a specific situation and possible outcomes, which themselves can have various outcomes.

Relationship diagrams can also present static relationships such as a map, which shows the relationships between different locations and the transportation methods between them (roads, bodies of water, paths and so forth).

## Mathematical

Mathematical diagrams show relationships using numbers. Charts and graphs are both subsets of **mathematical diagrams**. These diagrams present the viewer with a visual overview of numerical information at a quick glance. Viewers can understand general trends without reading specific numbers (although, the numbers are typically present on the diagram). A pie chart is a circular diagram that depicts ratios or fractions of a whole, in wedge shapes.

Mathematical diagrams such as bar graphs work particularly well to show differences in data over time because data can be visually displayed on both the X and Y access. Line graphs, bar graphs and histograms all use this format.