A Gantt chart is a type of bar chart

Bar chart

A bar chart or bar graph is a chart with rectangular bars with lengths proportional to the values that they represent. The bars can be plotted vertically or horizontally....

 that illustrates a project schedule

Schedule (project management)

In project management, a schedule consists of a list of a project's terminal elements with intended start and finish dates. Terminal elements are the lowest element in a schedule, which is not further subdivided...

. Gantt charts illustrate the start and finish dates of the terminal elements and summary elements of a project

Project

A project in business and science is typically defined as a collaborative enterprise, frequently involving research or design, that is carefully planned to achieve a particular aim. Projects can be further defined as temporary rather than permanent social systems that are constituted by teams...

. Terminal elements and summary elements comprise the work breakdown structure

Work breakdown structure

A work breakdown structure , in project management and systems engineering, is a deliverable oriented decomposition of a project into smaller components. It defines and groups a project's discrete work elements in a way that helps organize and define the total work scope of the project.A work...

 of the project. Some Gantt charts also show the dependency

Dependency (project management)

In a project network, a dependency is a link amongst a project's terminal elements.There are four kinds of dependencies with respect to ordering terminal elements :# Finish to start...

 (i.e., precedence network) relationships between activities. Gantt charts can be used to show current schedule status using percent-complete shadings and a vertical "TODAY" line as shown here.

Although now regarded as a common charting technique, Gantt charts were considered revolutionary when they were introduced.