Scrollbars vary by device and may be invisible on some mobile devices.
The rest of the text is hidden and so you won't be able to see it.
Lorem Ipsum Dolor Sit Amet
This bottom scroll bar is completely unnecessary, the div is big enough already.
Lorem Ipsum Dolor Sit Amet. Maecenas tristique venenatis magna quis cursus.
With 'auto', scrollbars are only added when needed.
Lorem Ipsum Dolor Sit Amet. Maecenas tristique venenatis magna quis cursus.
The content overflowing doesn't affect the rest of the page flow, so the browser view box does not expand to accommodate it.
Lorem Ipsum Dolor Sit Amet. Maecenas tristique venenatis magna quis cursus.