On many modern computers it is normal to have more than one hard drive and various optical disc readers (CD, DVD or Blu-ray). To all this we also have to add the USB pendrives that are usually used, the slots to read memory cards and the various external hard drives.
Do to this it is possible that there will come a moment in which you won't be at all sure what letter each of the drives has assigned, to be able to check and change it with ease you can always resort to DriveLetterView.
From a rather dull interface, it shows all the units that are connected to the computer and their data, and it offers the possibility to be able to change the letter assigned to each of the units, and even to delete the letter assigned to a USB pendrive that isn't connected at that moment.
Therefore, if you need to change the letter assigned to any drive with any complication, download DriveLetterView.