A line graph is a type of chart that displays information as a series of data points connected by straight line segments. It is commonly used to show trends over time, making it easy to visualize how values change. The horizontal axis typically represents time or categories, while the vertical axis represents the values being measured. Line graphs are useful in various fields, including science, business, and economics. They help in comparing different sets of data and identifying patterns, such as increases or decreases. By connecting the points, line graphs provide a clear visual representation of relationships between variables.