1. A Gantt chart is a type of bar chart, developed by Henry Gantt, which illustrates a project schedule. Gantt charts illustrate the start and finish dates of the terminal elements and summary elements of a project.
2. Terminal elements and summary elements comprise the work breakdown structure of the project. Some Gantt charts also show the dependency relationships between activities.
3. Gantt charts can be used to show current schedule status using percent-complete shadings and a vertical TODAY line

Disadvantages:-

1. A common error made by those who equate Gantt chart design with project design is that they attempt to define the project work breakdown structure at the same time that they define schedule activities.
2. Although a Gantt chart is useful and valuable for small projects that fit on a single sheet or screen, they can become quite unwieldy for projects with more than 30 activities.
3. Gantt charts only represent part of the triple constraint of projects, because they focus on schedule management.
4. 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.
5. Because the horizontal bars of a Gant chart have a fixed height, they can misrepresent the time-phased workload of a project, which may cause confusion especially in large projects.

Mile stone chart:-

• A milestone is used to represent groups of activities or significant events or commitments in the project.
• A milestone chart shows a group of milestones in an organized way similar to a Gantt chart with one milestone per line vertically with a description on the left and the milestone located horizontally along a time scale showing when it occurs.
• Milestones differ from the bars in a Gantt chart in that they show only a single date and are usually depicted as a triangle instead of a bar.
• Milestones can be shown in various colors depicting the status of the milestone.
• Milestones can also appear on Gantt chats; project management software supports the placement of milestones on Gantt charts and other project reports and displays generated by the software.