Date: Thu, 18 Mar 1999 18:01:37 -0500
Message-Id: <199903182301.SAA30669@envy.delorie.com>
From: DJ Delorie <dj AT delorie DOT com>
To: djgpp AT delorie DOT com
In-reply-to: <36F17BC3.78B926E4@cableol.co.uk> (message from Allens on Thu, 18
	Mar 1999 22:18:43 +0000)
Subject: Re: (fwd) Compression
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> I'm sure I heard somewhere that tgz's are based around the same 
> algorithm as zips, so why the mega space saving?  (Perhaps because
> they use a different algorithm?)

zip compresses each file separately, then stores them in the zip file
with headers.  tgz stores the files with headers, then compresses it
all at once.  Thus, not only is tgz compressing the headers, but it
also doesn't restart the compression algorithm for each file, so it
can recognize patterns in one file it saw in the previous file, and
compress better.