Because it is essentially redhat without the license fee. If you are in enterprise space and all that vendors certify for their software is RHEL, chances are very high it will work well on CentOS.
My understanding is that CentOS essentially takes the RHEL packages and removes the trademarks (the RH logo and name).
Entirely legal and ethical under the GPL, and RH benefits from all the folks who know the RHEL system because of exposure to CentOS - when they're recommending a supported version of Linux, it's likely to be RHEL.
I think if CentOS were selling support contracts, that would be pretty bad. RedHat makes their money on support contracts. By using CentOS, you're more likely to switch to RedHat when you need to pay for a bunch of support.
It feels a little bit more moral to load CentOS on a bunch of systems, than to load Red Hat on them and only pay for one support contract. As an analogy, Microsoft probably prefers people to pirate Windows than to switch to Linux/Chromebook.
It's been a while since I looked, but I believe a few CentOS developers get paid by redhat, or if not, at least have alternate @redhat.com addresses. My impression has always been that CentOS and Red Hat have a good enough relationship that CentOS would not want to jeopardize that. Additionally, Red Hat benefits from having one of, if not the most common server distro (the numbers are hazy) based on their product.
The truth is, Red Hat is the only linux distro I can think of (besides maybe SuSE, but I don't know much about it) that has really made a significant push to take over the enterprise market from Microsoft (and now they've moved to trying to do the same thing to VMWare).
They simply repackage and rebrand RHEL, then give it away for free. If anything I'd be quicker to call RHEL the free rider on the hundreds of pieces of OSS software they use (but I do not make that argument).
If you want a warranty/support contract, definitely purchase RHEL. If you don't need that, but want enterprise grade stability and compatibility, use CentOS. If you want to run Linux on your laptop, don't use either.
> If you want to run Linux on your laptop, don't use either.
Actually CentOS 6.4 has been the most reliable thing on my Lenovo T61, T400 and Dell T3500. Everything works from hibernate, sleep, WiFi, SAS, SSD's out of the box with no configuration.
This is the polar opposite of Ubuntu, Debian stable, Debian testing and Mint which are royal bastards to get off the ground.
Never again. Always seemed laggy. I just loaded Scientific Linux 6.3 on 3 old thinkpads this past weekend. As you said, everything works. No "sudo vi /etc/X11/xorg.conf", no modprobe & ndiswrapper. Red Hat was my first peek at linux, so I'm a tad nostalgic (remember 9.1? crux, luxi sans?).
That's good because given the amount of code Red Hat contribute back to the community, including buying proprietary tools and open sourcing them, you'd look like a complete idiot.
Note that Oracle is/was doing the same thing (repackaging RHEL) with "Unbreakable" Linux, and they are selling support for it.
They also offer their "own" kernel.
