What does "sudo apt-get dist-upgrade" do? [duplicate]

Question

I would like to know more about this command:

sudo apt-get dist-upgrade

Answer 1

See man apt-get:

 dist-upgrade
           dist-upgrade in addition to performing the function of upgrade, also intelligently handles changing
           dependencies with new versions of packages; apt-get has a "smart" conflict resolution system, and it will
           attempt to upgrade the most important packages at the expense of less important ones if necessary. The
           dist-upgrade command may therefore remove some packages. The /etc/apt/sources.list file contains a list of
           locations from which to retrieve desired package files. See also apt_preferences(5) for a mechanism for
           overriding the general settings for individual packages.

Answer 2

To learn about commands, read their manual page (short "manpage") using the man command.

E.g. to learn about apt-get, type this command:

man apt-get

The manual will also contain a description of the dist-upgrade argument:

   dist-upgrade
       dist-upgrade in addition to performing the function of upgrade,
       also intelligently handles changing dependencies with new versions
       of packages; apt-get has a "smart" conflict resolution system, and
       it will attempt to upgrade the most important packages at the
       expense of less important ones if necessary. The dist-upgrade
       command may therefore remove some packages. The
       /etc/apt/sources.list file contains a list of locations from which
       to retrieve desired package files. See also apt_preferences(5) for
       a mechanism for overriding the general settings for individual
       packages.

To exit the manual viewer again, simply press Q.

The sudo is needed because the command needs root privileges in order to perform the necessary system-wide operations.