Package Basics

TDS, TeX Directory Structure http://www.tex.ac.uk/cgi-bin/texfaq2html?question=41

TDS is a standard way of organising all the \TeX -related files on a computer system.

The TDS reserves the name texmf as the name of the root directory (folder) of the hierachies. Files supplied as part of the distribution are put into the standard hierarchy. The location of the standard hierarchy is system dependent, but on a Unix system it might be at /usr/local/texmf, or /usr/local/share/texmf, or /opt/texmf, or a similar location, but in each case the TeX files will be under the /texmf subdirectory.

There can be multiple 'local' hierarchies in which additional files can be put. In the extreme an installation can have a local hierarchy and each user can also have an individual local hierarchy. The location of any local hierarchy is not only system dependent but also user dependent. Again, though, all files should be put under a local /texmf directory.