Also named line chart, this is used to visualize the value of something over time. It helps showing multiple series of closely related series of data. They are formed by a horizontal x-axis and a vertical y-axis. Most of times the x-axis is a timescale or a secuence of intervals and the y-axis has a quantitative value. The line graphs are drawn by plotting data points on a Cartesian coordinate grid, then connecting them with a line. Directions of the lines usually show what happens with the data in a simple way, an upward slope indicates an increase in values and a downward slope the decrease fo values. In this way the line's journey accross the graph can create a different pattern reveling trends.