The xgraph program draws a graph on an X display given data read from either data files or from standard input if no files are specified. It can display up to 64 independent data sets using different colors and/or line styles for each set. It annotates the graph with a title, axis labels, grid lines or tick marks, grid labels, and a legend. There are options to control the appearance of most components of the graph. Originally written by David Harrison, the code is mostly/completely unchanged since December 1989, when xgraph-11 was released. The program relies only upon Xlib calls (and not any specific toolkit), so it should work on all X systems.