Lines can have additional properties such as linewidth. You can associate these various properties, as well as equivalent properties for point symbols, into user-defined "linestyles" using the command `set style line`. Once you have defined a linestyle, you can use it in a plot command to control the appearance of one or more plot elements.
Whereas `linetypes` are permanent (they last until you explicitly redefine them), `linestyles` are temporary. They only last until the next reset of the graphics state.
Examples:
# define a new line style with terminal-independent color cyan, # linewidth 3, and associated point type 6 (a circle with a dot in it). set style line 5 lt rgb "cyan" lw 3 pt 6 plot sin(x) with linespoints ls 5 # user-defined line style 5