![[Main Page]](/skins/common/images/wiki.png)
The Eternal September is the name given to the period of time following AOL's opening of Usenet access to all subscribers of its internet access. Usenet regulars see it as the turning point in the decline of Usenet. More generally, an Eternal September Moment is the point were the early adopters of some community consider it "lost" in some regard.
Usenet
Back in the early days of Usenet, it was mostly students and academic researchers who used Usenet. The general public did not have, or even want, access to the newsgroups. Every September, the new influx of students at colleges who gained access to Usenet for the first time, would make a number of etiquette mistakes, but would be corrected by the culture and settle in in time for the next round the following year.
However, in 1993, AOL gave its sizable userbase access to Usenet for the first time. Suddenly, newsgroups were flooded with newbie questions. The new users didn't know about the complex social rules that had organically grown up in the community, and few tried to learn anything about the culture. It's entirely questionable whether some users even realized that Usenet wasn't an AOL product, or had existed before then.
In January 1994, Dave Fisher noted that 1993 would go down in history as "the September that never ended".
And thus, the Eternal September meme was born.
General Implications
I think that every community on the net of any size eventually has its own Eternal September moment. Some are, of course, easier to recognize than others. Slashdot's came with the creation of Digg, and Digg's with the creation of Reddit. Each time, some mass of users of the old service realizes that, for better or for worse, the "newbies" outnumber them. For example, on Wikipedia, a member known as Fonzy said this about his departure in 2004:
That feeling of being on the forefront of the trend, of having been there first; it's important to many users.