A line chart is a type of graph 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 changes in data. The horizontal axis typically represents time or categories, while the vertical axis represents the values being measured. Line charts are particularly useful in fields like finance, science, and business for tracking performance, sales, or other metrics. They can represent multiple data sets by using different colored lines, allowing for easy comparison between different variables or groups.