What is the primary use of a line graph?

A line graph is primarily used to show changes over time. This type of graph effectively plots data points along a timeline, making it easy to visualize trends, patterns, or fluctuations in the data as it progresses. For instance, it can illustrate how temperatures fluctuate throughout the year or how a patient's vital signs change over a period. The connecting lines between the data points allow observers to see how variables evolve, making this graph an ideal choice for tracking changes and trends rather than simply comparing discrete values or showing proportions.