A Gantt chart is a horizontal bar chart developed as a production control tool in 1917 by Henry L. Gantt, an American engineer and social scientist.
Frequently used in project management, a Gantt chart provides a graphical illustration of a schedule that helps to plan, coordinate, and track specific tasks in a project. Gantt charts illustrate the start and finish dates of the terminal elements and summary elements of a project.
A Gantt chart is constructed with a horizontal axis representing the total time span of the project, broken down into increments and a vertical axis representing the tasks that make up the project.
In the 1980s, personal computers allowed for widespread creation of complex and elaborate Gantt charts. The first desktop applications were intended mainly for project managers and project schedulers. With the advent of the Internet and increased collaboration over networks at the end of the 1990s, Gantt charts became a common feature of web-based applications, including collaborative groupware.
Gantt charts give a clear illustration of project status, but one problem with them is that they don’t indicate task dependencies – you cannot tell how one task falling behind schedule affects other tasks.
Gantt charts only represent part of the triple constraints (cost, time and scope) on projects, because they focus primarily on schedule management.
Moreover, Gantt charts do not represent the size of a project or the relative size of work elements, therefore the magnitude of a behind-schedule condition is easily miscommunicated.
If two projects are the same number of days behind schedule, the larger project has a larger effect on resource utilization, yet the Gantt does not represent this difference.