Aneuch is a wiki engine being developed by Aaron Graves. The engine is a single Perl script, with optional plugins. When installed, it generates a web site where users can read, change, create and even delete pages. This creates an unparalleled level of collaboration that most websites will never see. As an example, Wikipedia is probably one of the most well-known wiki implementations in the world (see also WhatIsAWiki).
Aneuch is free in every sense of the word (free as in beer, and free as in speech), being licensed under the BSD License. Many FOSS (Free and Open Source Software) projects are released under the GNU GPL or similar license (sometimes called CopyLeft), but there are quite a few projects out there that use the BSD license. (For a history on the BSD licenses, see https://en.wikipedia.org/wiki/BSD_licenses and http://www.freebsd.org/doc/en_US.ISO8859-1/articles/bsdl-gpl/article.html).
Using this license is effectively a statement that you can do anything with the program or its source, but you do not have any warranty and none of the authors has any liability (basically, you cannot sue anybody). This new BSD license is intended to encourage product commercialization. Any BSD code can be sold or included in proprietary products without any restrictions on the availability of your code or your future behavior.
While the mainline Aneuch development will always remain free and open source, users are able to incorporate code from Aneuch (or a complete derivative thereof) into their commercial product. They would not owe me any royalty, they must simply just state something along the lines of "Portions of this program Copyright (C) Aaron Graves."
See also [Vision and Mission?]
Aneuch chooses to use your filesystem to store its data, rather than a database. While it is certainly possible to have a plugin that will tell Aneuch to use a database instead (indeed, such a plugin is planned for development), that functionality will likely not be included in the base code.
Not only would using a database complicate installation, it would complicate development. While MySQL is certainly the most popular choice of database system on a *nix server, many people use PostgreSQL, and even Oracle. Heck, you could even want to use MsSQL on a Windows server!
For an interesting comparison by Radomir Dopieralski, see Comparing Filesystems and Databases. For moving to a database based back-end, see Considerations for moving to a DB back-end.
Aneuch was started from scratch in June of 2012. Initially it was very rudimentary and spartan. It displayed pages and allowed basic editing. No page history was stored, there was no way to check a list of recent changes, etc.
Then I came across Oddmuse, another wiki engine, and began adding features to Aneuch that I liked from Oddmuse. Without exchanging any actual code, I began implementing things one by one until Aneuch became what it is today. (See About)
Yes, I know there are a bunch of other wiki engines out there. Some are Perl, most are PHP. There are a few in other languages, such as Ruby. In fact the original wiki, WikiWikiWeb, has a list of some of them. There's also a list on WikiMatrix. But for me, part of the fun in building a wiki site was building the complete site, including the wiki software itself. Not everyone can do this, and many others that could wouldn't even bother.
I don't recall now exactly the website I used, but I had some trouble initially coming up with a name for the wiki engine, so I sought out a random project name generator on the web. The one I found allowed you to customize the commonality of the name it chose (ranging from commonly used words, to the not so commonly used). I set it on the highest level, which would produce many words I had never even heard of. I looked up the definition of each, and continued on until it stopped on Aneuch. The definition came back as "enough," and I decided that was it. I wanted the wiki to be "enough" for everyone, so the name fit perfectly.