You can determine what happens when you have more stuff in a container than there's room for by using overflow. If I were to print out the complete works of Shakespeare in a 40-pixel wide, 40-pixel high <div>, what should happen? Well, that's what overflow is for.
Its values are clip, scroll, and none. The clip value means that if the contents are too large, they just get chopped off and aren't rendered. This is the default behavior of the browsers (even if the spec says differently). The scroll value places scrollbars on the parent container and allows you (the reader) to scroll through the content. This is superfantastic, since it accomplishes a good deal of what frames are used for 60 percent of the time. Plus, you (the author) don't have to make silly workarounds, like a scrollball. I've never seen the none value work correctly on any browser as of yet, but if it were to magically start working, it would cause contents to bust their way out of their parent and be rendered as if there were no walls.
