CentOS was, as you say, a community developed drop-in replacement for RedHat RHEL that subsumed a number of earlier RPM-based distributions in the early-mid 2000s. It was _widely_ used: in the 2010s the CentOS install base was on the same scale as Debian.

The CentOS governance structure and trademarks were effectively absorbed by RedHat, Inc in 2014.

In 2020 RedHat unilaterally "refocused" CentOS from being essentially "Community RHEL" to being "CentOS Stream" which is more or less a stability channel somewhere between Fedora and RHEL. This doesn't suit the needs of many folks who were running CentOS, and was done so abruptly that they even broke support window promises on the current release at the time, so it generated some bad feelings.

AlmaLinux and RockyLinux are projects that promptly spun up to replace CentOS in the "Community RHEL" role, from different prominent members of the community: Alma from CloudLinux, Inc. and Rocky from Greg Kurtzer of [CentOS cofounder,Warewulf,Singularity/AppTainer, CIQ] fame.

I don't know all the inside politics, but the reason there are two appears to be partly related to concerns about governance structure to prevent another round of commercial capture of community resources.

I don’t have any numbers to back me up— just a hunch and from my own experiences in the industry, I would think that in the 2010’s the install base of Debian would have paled in comparison to CentOS (this would be on the interwebs of course). I don’t know that you could say that they were on the same scale, with my suspicion that CentOS was way more prevalent.

I’d be interested in stats on that from 2010s, and now. I’d even suspect that even today, EL as a whole might outnumber Debian, but perhaps not Ubuntu or Debian/Ubuntu combined (even notwithstanding the rise of containers).

I was going by this low hanging chart from the server market: https://w3techs.com/blog/entry/debian_is_now_the_most_popula... which seems credible with my memories from industry buddies at the time.

Though, as you allude, I bet a lot of CentOS installations aren't as visible, given its prevalence in things like compute clusters, dev systems, and that sort of thing.

(I have no horse in the race, my personal day-to-day use machines are mostly Arch boxes, and I regularly work on both Debian and CentOS-transitioning-to-Rocky machines.)

Thanks for the link! Seems as though Debian was more popular than I realized on the internet..

https://rockylinux.org/ :

  Rocky Linux is an open-source enterprise operating system designed to be 100% bug-for-bug compatible with Red Hat Enterprise Linux®. It is under intensive development by the community.

It's the only above the fold text on the home page.

The About page is

  ...Red Hat announced that they would discontinue development of CentOS, which has been a production-ready downstream version of Red Hat Enterprise Linux,... In response, ... he would again start a project to achieve the original goals of CentOS.

You know, I never ended up navigating to that main page. There wasn't an option for it anywhere in the drop down menu at the top, or in all the options at the bottom. As far as I can tell, the only link to it is the logo graphic? So maybe all they need to do is add a "main page" option to the menu and it will be more ergonomic?

While it might be the case that many websites have a dedicated "home" menu item, I think even more websites use the pattern of the corner logo serving as such, to the point that if a site offers both, I'm using the logo every time. It's one of those things that perhaps verges on anti-pattern in discoverability, but is so ubiquitous that most people probably don't even think about whether that's true or not.

> The about page mainly just talks about the legacy of the name.

"On December 8, 2020, Red Hat announced that they would discontinue development of CentOS, which has been a production-ready downstream version of Red Hat Enterprise Linux, in favor of a newer upstream development variant of that operating system known as "CentOS Stream". In response, original founder of CentOS, Gregory Kurtzer, announced via a comment on the CentOS website that he would again start a project to achieve the original goals of CentOS."

I think the very first paragraph on the about page just about sums it up. It's a production-ready downstream version of Red Hat Enterprise Linux.

CentOS was nice for two reasons:

1. Big "enterprise" software would run on it because it was basically RedHat.

2. It had an exceptionally long support cycle, so you could setup a machine and ignore it for ten years.

To clarify your second point -- you can maintain security fixes for 10 years without having to worry about random changes that may break your installed apps and workflows.

Which it did, quite often. There would often be bugs that existed between kernel 2.6.300 and 2.6.336 or some nonsense. The idea is nice, but in practice all of that backporting just seemed like a lot of work for not much benefit.

There is a bit of history behind it and other Red Hat Enterprise Linux clones. Originaly there was CentOS which was the "open source" / free version of RHEL. It was known for stability and reliability as a Linux distro for enterprise applications. CentOS was also 1-1, bug-for-bug replacement for RHEL.

This was good for a long time, but Red Hat dropped support for CentOS a few years back and stopped updating it. So Rocky Linux, Alma Linux, and others popped up to replace CentOS.

While that's super valid, they are catering to existing CentOS users who are being forced to find an alternative since CentOS was discontinued. I'm not surprised that they aren't focused on trying to bring in new users, they've got a lot of work to do and the userbase already exists.

Well you could argue the name needs some explanation. The first time I heard it my mind immediately jumped to the dictionary definition of the word rocky - "difficult and full of obstacles or problems."

It seems like a fine name. I personally didn't link it to that connotation, and instead initially thought of Rocky and Bullwinkle, and a distant relative of a past generation. For all I know the honored co-founder was a curmudgeon, so maybe it's an especially clever pun?

If I were tasked with improving the about page, I would probably use the about page to explain the purpose and merits of the operating system. I would move the explanation of the name to the first question in the FAQ, or to a separate "Rocky's Legacy" page. Mainly, it would depend on whether the guy was known to be modest or proud. Then that section could be a true tribute without any risk of compromising the readability of the site.

Rocky and CentOS are both based on Red Hat Enterprise Linux (RHEL).

CentOS used to be a free and open source downstream version of RHEL. Keeping the history short: Red Hat effectively acquired CentOS and discontinued it as a downstream version of RHEL. They turned it into 'CentOS Stream', which is, more or less, a continuously delivered upstream version of RHEL. This isn't acceptable for a large number of the CentOS user base.

One of the original founders of CentOS, Gregory Kurtzer, started Rocky as an alternative. It's basically what CentOS used to be: a free and open source downstream version of RHEL.

Huh, that's interesting. Isn't Fedora the upstream version of Red Hat already? Or is the main distinction that CentOS Stream is rolling release?

I'm pretty much on the complete opposite end of the Linux ecosystem, working primarily on embedded systems.

Fedora's more playground / cutting edge technology demonstrator for Redhat developers. Anything showing up in Fedora won't be included in RHEL for several years, assuming everything goes well.

CENTOS Stream slots in between Fedora and RHEL, keeping a bit ahead of the RHEL stable release.