XPM (X PixMap) is a powerful and portable format for storing/retrieving pixmaps to/from files. It provides the easiest way to load a graphical image into a GTK+ application. Moreover, the graphical data can be embedded in the application itself.

Briefly, the XPM format consists of a string describing its dimensions and number of colors, followed by the color table, and finally by the image data utilizing the characters mapped in the color table. Here's a sample: 

                         "16 16 6 1",
                         "       c None s None",
                         ".      c black",
                         "X      c red",
                         "o      c yellow",
                         "O      c #808080",
                         "#      c white",
                         "                ",
                         "       ..       ",
                         "     ..XX.      ",
                         "   ..XXXXX.     ",
                         " ..XXXXXXXX.    ",
                         ".ooXXXXXXXXX.   ",
                         "..ooXXXXXXXXX.  ",
                         ".X.ooXXXXXXXXX. ",
                         ".XX.ooXXXXXX..  ",
                         " .XX.ooXXX..#O  ",
                         "  .XX.oo..##OO. ",
                         "   .XX..##OO..  ",
                         "    .X.#OO..    ",
                         "     ..O..      ",
                         "      ..        ",
                         "                "