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 how values change. 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 changes in data, such as stock prices or temperature variations. They help viewers quickly identify patterns, peaks, and troughs in the data, facilitating better decision-making and analysis.