A Gantt Chart is a horizontal bar chart that illustrates a project’s schedule. It is commonly used in project management. It is named after its creator Henry Laurence Gantt around 1910. Microsoft Project or Oracle's Primavera are two commonly used software to build Gantt charts. They include many functions that link to other project elements to help you manage a project, but you can build a simple Gantt Chart with a spreadsheet.
Here is a basic example to illustrate:
The lefthand column lists the tasks required to complete a project in chronological order. The chart shows time passing from left to right and each task will have a bar (yellow in our example) showing the estimated duration required to complete including the scheduled start-to-end date. For example, Task 1 will take the first two days to complete.
Since project tasks can often be completed simultaneously, you may see multiple tasks in progress during one unit of time (days in this example). If a task is dependent on another task being completed first, its scheduled start will have to follow the end of that task. However, the goal is typically to start any particular task as early as possible.
Alignment with Procurement Schedule
In project work, materials and equipment have to be delivered to the project site to facilitate construction or installation work. Project schedules will often have what are called Required on Site (ROS) or Required at Site (RAS) dates for these items. A supply chain professional will have to align the delivery dates with other tasks in the project schedule to prevent any delays. See my post on project procurement to read about some of the considerations of time requirements in supply chain management.