Line chart is formed by line segments connecting each data points. Normal practice is to set horizontal axis (X axis) as independent variable (such as time, temperature, etc.), and the vertical axis (Y-axis) as dependent variable in order to display trend of dependent variable corresponding to different values. Any trends and cycles can be viewed clearly on line chart. The most common usage of line chart is to set the horizontal axis as time to analyze the trend of data over time, such as demographic changes, inflation, etc.