A timeline is a way of displaying a list of events in chronological order, sometimes described as a project artifact . It is typically a graphic design showing a long bar labeled with dates alongside itself and (usually) events labeled on points where they would have happened.
Timelines are often used in education

Education

Education in its broadest, general sense is the means through which the aims and habits of a group of people lives on from one generation to the next. Generally, it occurs through any experience that has a formative effect on the way one thinks, feels, or acts...

 to help students and researchers with understanding events and trends for a particular subject.
Timelines are particularly useful for studying science, as they convey a sense of change over time.