A line chart is a graphical representation of an asset's historical price action that connects a series of data points with a continuous line. This is the most basic type of chart used in finance, and it typically only depicts a security's closing prices over time. Line charts can be used for any time frame, but they most often use day-to-day price changes.
A line chart provides traders with a visualization of where the price of a security has traveled over a given period. Because line charts usually only use closing prices, they reduce noise from less critical times in the trading day, such as the open, high, and low prices. Line charts are popular with investors and traders because closing prices are a common snapshot of a security's activity.