What is a trend line used for in Tableau?

A trend line in Tableau is mainly used to illustrate the overall direction or pattern in a dataset over time or across different variables. By adding a trend line to a visualization, users can easily identify whether data points are increasing, decreasing, or remaining stable. This provides valuable insights into the underlying trends within the data, which can aid in forecasting and decision-making.

While trend lines do not specifically display seasonal variations (option A) or highlight individual data points (option B), they provide a smoothed view of the general movement of the data as a whole. Additionally, trend lines do not perform calculations like totals across different categories (option D); instead, they focus on summarizing the trajectory of the data. Thus, understanding trends helps analysts and stakeholders make informed predictions and strategies based on observed patterns.