What is this?

This is my collection of plaintext versions of the Jargon File, going back who-knows how long; the earliest "last changed" date we have is 1981-07-22, and that's on what seems to be the sixth version of the file archived here.

What do the version numbers mean?

1.1.0, 1.2.0, and 1.4.0 are the numbers assigned to early Jargon Files by Eric S. Raymond during the period the files were available from his website. 
1.3.0 was a file identical to 1.2.0, and so is not included separately.
1.0.3, 1.0.4, and 1.0.5 are versions that appear to predate what ESR called 1.1.0, and so were given arbitrary preceeding numbers in apparent order of creation.
1.1.2, 1.1.3, and 1.1.5 seem to date to the period between what ESR called 1.1.0 and 1.2.0, and so were given arbitrary preceeding numbers in apparent order of creation.
2.1.1 and later have the numbers given to them by ESR.

Why zip and gzip?  Why not (bzip2|7zip|etc.)?

Zip is everywhere.  It's built into Windows XP and Mac OS X, Info-Zip's Unzip runs on a vast number of architectures, and there are other unzippers out there for things like the Apple II GS and Commodore 64.  Nothing matches zip as a universal compressed file format, whatever its deficiencies. 

Gzip is almost as common as zip, and has the useful property that clicking on a txt.gz will display the text in most modern browsers.

Okay, what files are the most interesting?

In my opinion?

• 1.0.3, the olderst recovered version of the File
• 1.5.0, the text of the original Hacker's Dictionary
• 2.1.1, the first version of the modern File
• 2.9.6, the text of the first edition of the New Hacker's Dictionary
• 3.0.0, the text of the second edition of the New Hacker's Dictionary
• 4.0.0, the text of the third edition of the New Hacker's Dictionary

You're missing X!

Yep, I am.  We probably will never have a complete archive of the primordial versions.  Of the later versions, what we know we're missing are:

2.1.[2-4] -- I've never seen a citation from or pointer to these files; ESR's website mentions them, however.
2.4.2  -- Cited in older versions of FOLDOC and sources quoting those versions of FOLDOC -- Google for "Cookie Monster" to see what I mean.
2.9.[1-5,7] -- Again, I've never seen a citation from or pointer to these files; ESR's website mentions them, however.

1.3.0 is not missing; the version given that number is the same as 1.2.0.

If you have any of the above, or any "1.x" versions not included in this archive (please check with a file comparison utility), don't hesitate to send them to jargon@jargon-file.org