What is CTAN?
The acronym stands for “Comprehensive TeX Archive Network”, which
more-or-less specifies what it’s for:
The basic framework was developed by a TUG working group set up
to resolve the (then existing) requirement for users to know on
which archive site a particular package might be found.
- The archives offer a comprehensive collection of TeX resources.
- The content is made publicly accessible, via the internet.
- CTAN is a network of archives, which strive to
stay in step with one another.
Actual implementation offers three distinct types of host:
Note that there is nothing to prevent any archive from supporting
other functions, so a CTAN mirror may also operate as a
CPAN (Perl) mirror and as a SourceForge (general free software)
mirror, and …
- Core archives
- Which form a small, tightly-coupled set of
machines, which perform management functions as well as serving
- Mirror archives
- Which do no more than take regular copies
of core archives, and serve them; and
- Archive selector
- Which is a meta-service, which routes requests
to an apparently “local” mirror (“local” is determined by an
algorithm that uses your net address to determine where you are, and
then selects a mirror that’s close).
Functions that distinguish core archives are:
- Uploads: users may submit new (or updated) material via the
upload redirector. Significant changes to the
archive are reported via the mailing list email@example.com
- Weak consistency: changes to the content of the archives are
rapidly distributed to all core archives. (Consistency is ‘weak’
since changes can take several minutes to propagate.)
- Providing distribution (texlive and MiKTeX) support.
- Catalogue maintenance.
- Mirror monitoring.
Users may make direct contact with the
CTAN management team.
Users should ordinarily download material from CTAN via the
archive selector: this uses the
mirror monitor’s database, and uses the caller’s geographical location to
offer an efficient choice of “sufficiently up-to-date” mirror site for
you to connect to. This procedure has the advantage of distributing
the load on CTAN mirrors.
Note that all the download links, given in the web representation of
these FAQs, are set up to use the mirror selector.
This answer last edited: 2013-05-21
This question on the Web: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=ctan