This is the download file that contains all of ClassWeb's contents, including the directory structure. This bundling of all of the ClassWeb files together is convenient for downloading because the relative location of the of files in the directory structure is maintained, and it is quicker than downloading them individually.
A collection of files, under Linux/Unix, packed together for easy distribution. From Tape ARchive. Directories are preserved.
a collection of several files and/or directories in one file
an archive of files file, while
a Unix file that packs together a whole set of files
(n.) A file, usually saved on a tape, that contains archive d data which was created by the UNIX® tar program.