If you're downloading a large file and it hasn't yet completed downloading, you may have to eventually shut down your system and attempt to download it later. With these specialized download managers, you can resume your web (HTTP or FTP) download at another time without interruption.
One of the most important features of these download managers is to maintain the integrity of the files so that they are not corrupted after they have completed downloading. While most download managers can pause and resume file downloads, not all of them can do that without corrupting the file when it is completed.
This list of download managers are able to pause and resume file downloads from FTP and HTTP sites.