If you have more than one computer running Ubuntu (or Debian), or maybe you are experimenting with different installations of Ubuntu using something like VirtualBox, you might find yourself using a lot of bandwidth and time when downloading packages from the Internet to update or add capabilities to your machine. By default each installation of Ubuntu will go directly to the Ubuntu download servers to get packages, producing a situation where you are downloading the same file multiple times through your connection to your ISP. There is an alternative to this situation though, you can download the packages through a host on your own network that will act as a cache. The next time any machine wanting that file requires it, the cache will serve its own copy, instead of having to download it again. This is a lot quicker, as the speed in your internal network will be much higher than the speed of the connection to your ISP, it is also a great bonus if you have maximum download allowances as part of your Internet connectivity package. Setting this up is not too difficult, thanks to a program called Apt-cacher.