The term Star Formation History (SFH) often is used for the function or graph of Star Formation Rate (SFR) over time. The concept of SFHs of galaxies is often used, as well as for other types of regions, e.g., the whole universe, Galaxy Clusters (CL), galactic clusters (e.g., Open Clusters or Globular Clusters (GC)), Star-Forming Regions (SFR), etc. The graph would show SFR (or possibly the SFRD) against years or Redshift (z).
Such a history for a type of galaxy may be constructed by looking at the observed SFR of many examples over a long course of time. For individual nearby galaxies, such a history may be constructed by determining the age of individual stars (or collective stellar-age-population statistics derived from the Electromagnetic Radiation (EMR) of the galaxy or regions within it) and extrapolating back to the Star Formation (SF) at the time the stars were born. Synthetic SFHs can also be constructed from simulations, for comparison with constructions, to improve and/or confirm both the construction and the simulation.