timeline

A timeline is a representation that organizes events along a chronological axis, usually a line marked with dates or time spans. It can be graphical, such as a horizontal or vertical line with labeled points, or textual, listing events in order. Timelines help visualize sequences, durations, and relationships among events, making it easier to understand history, processes, or plans.

Historically, humans have recorded time through chronicles, regnal lists, and calendars. The modern term timeline and the practice of displaying events along a line gained prominence in educational and informational contexts, expanding with digital tools that offer interactive timelines.

Common types include historical timelines, life timelines (biographical), and project or process timelines, which emphasize milestones and deadlines. Timelines can show exact dates or approximate periods and may indicate uncertainty or overlapping events.

Constructing a timeline involves choosing a scope, gathering dates or estimates, placing events along the axis in order, and annotating entries with brief descriptions. The format can emphasize duration (long bars), frequency, or causality through linked events.

Digital timelines enable filtering, zooming, and multimedia, and are widely used in education, journalism, and research. Limitations include simplification, cultural bias in dating, uneven precision, and the risk of implying erroneous cause-effect relationships.

See also chronology, calendar, time axis, and Gantt chart.