cout.width()

I am quite good at C++ programming (windows + OpenGL), but not at DOS. My C++ course requires that we know how to use cout.width(). I am really puzzled as to what this does and how to use it. The textbook simply gives code, and shows the output. I really don't get it. Can someone please tell me more about it and EXACTLY what it does? Thank you!

http://130.70.82.204/fdd/cpp_pdf/chap03.pdf
This pdf file gives a good explanation of it on the second page. It was surprisingly simple to find. It only took me about three minutes when I put cout.width() into google. A couple minutes searching for things usually brings great results.

I apologize. Usually, I do search more extensivly before asking, but I realized my test was today! =P Thank you!