How can I make a box which has a title written on it and a plus sign(+) on the side  and when I click the plus sign the box expands or opens and the plus sign becomes minus sign(-) .Then again when I click the minus sign the box contracts back to its original position and the minus sign again becomes plus sign . Can I make this kind of box purely in javascript and XHTML ? If yes then please help me by providing the code to do so and explaining it how it works. Thanks