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 useful in various fields, including finance, science, and business, as they help in analyzing patterns and making predictions. By observing the slope and direction of the lines, viewers can quickly identify increases, decreases, and overall trends in the data being presented.