Lines are among the most frequently occurring elements in Matplotlib visualization, from those representing data series to those marking axes, grids, and outlines of any shape. Hence, it is important to understand how we can adjust line style. Lines in Matplotlib are controlled by the Line2D class. The object-oriented structure of Matplotlib makes it easy to adjust line styles through keyword arguments with similar grammar in each API. Here, we shall introduce the several most commonly tuned aspects of Matplotlib lines.