Here you can choose which partition(s) you wish to format. Any data on partitions not marked for formatting will be saved. Usually at least the partitions DrakX selected, need to be formatted Click on Advanced to choose partitions you want to check for so called bad blocks If you're not sure you have made the right choice, you can click on Previous, again on Previous and then on Custom to get back to the main screen. In that screen you can choose to view what is in your partitions. When you are confident about the selection, click on Next to continue.