The package managers in Debian make it easy to upgrade software packages, and even upgrade to a new, major release level. Upgrades don't require major server downtime, although if they involve major software changes that modify how the software is configured or behaves, additional work may be required after the upgrade to return service to normal. Non-Debian repositories can be added so that the package managers can update non-Debian software just as easily as official Debian packages. Ifsoftware isn't available in Debian format, it can be packaged using the same tools Debian developers use, so that Debian package managers will handle it as well.
Usually after an installation or upgrade, there are additional steps that must be taken. The major one is package configuration, which we will cover in the next chapter.
