Everywhere in our daily lives and in almost all professional fields, plots surround us. Most people find it very difficult to detect and understand the cause-effect relationships in mere numerical tables. Visualizing data helps humans quickly capture relationships between one or more variables. Therefore, the graphical system is an integral part of R.
When you visualize data, the resulting plot appears on a graphical device. There are three different types of devices:
File devices, also called vector output, including PDF, PostScript, xfig, pictex, SVG, and win.metafile.
Bitmap devices, including the formats PNG, JPEG, TIFF, and BMP.
Screen devices, which in turn are the services of the different platforms. For Mac OS X, it is quartz(), for Windows, it's windows(), and for Linux/Unix, the screen device is launched by x11().
When you create a plot, this graphic will be sent to your screen device. There is only one screen device per...