A timeline is the presentation of a chronological sequence of events along a drawn line that enables a viewer to understand temporal relationships quickly. The term is also sometimes extended to mean a chronology that is tabular, year-by-year paragraphs or purely conceptual. Increasingly, timelines are illustrated in infographics combining text and graphic images for a better presentation.
Timelines are useful to document any type of development, providing an easy-to-understand history and helping viewers to understand past and ongoing trends. The tools are also useful for management tasks. In project management, for example, a timeline illustrates milestones, deadlines and other significant dates and events over the lifecycle of the project, clearly tying goals to specific dates. Annotations to the timeline can document actual progress.
See a brief history of the Internet in this video timeline: