by Byron Mudry on Apr 01, 2006
With patch 1.10 came a new feature that is supposed to decrease our download time when patches are released. Here is what was said in the Blizzard forums about it:
With the 1.10 patch we have integrated a new content delivery system called the Blizzard Background Downloader. This program will run seamlessly with World of Warcraft and download upcoming content prior to the release of a patch. With use of this program a minimal amount of data will be needed during the next actual patch release and help to decrease the amount of time spent downloading the patch. The Blizzard Background Downloader uses the same protocols and connection methods as the Blizzard Downloader, some customers may need to configure their various network protection programs and hardware to take full advantage of it.
You can check the Blizzard Technical information site for complete details here.