5 Distributions that changed Linux By jfd5xte 

(originally, Red Hat Linux)

While I respect that Slackware, and several others including SuSE, pre-dated Red Hat, it was Red Hat that really opened the doors to a sizeable user-base. Back in the mid-thru-late 90's, a Red Hat user did require a measure of computer expertise, but learning unix could be done after the system was up and running as opposed to as a pre-requisite.

After the #1 spot, ranking the most influential distro suddenly becomes more challenging. Others could certainly make an argument for moving something else to the level of #2 distro.

The reason RHEL is number 2 for me is because it has consistently proven to be profitable and business-worthy. This is a MAJOR milestone. While other linux businesses, even distributions like SuSe/Novell, have seen business growth and profit, RHEL has been the banner carrier for the business of open source software and linux.

Had it not been for RHEL, it's not clear whether IBM, Dell, and the IT industry at large would have embraced linux as strongly as it has. Microsoft, now, can't help but play ball in the Linux space.

The DEFINITIVE community distribution.

Debian is a strong candidate for number two... even number one isn't out of the question.

The packaging toolset (dpkg, apt, et. al) that Debian contributed to the community has set the bar by which all other toolsets have been measured for over a decade.

Beyond any of the technical justifications for superiority, Debian has always been about community. Most successful distributions have been commercial-based, incentivized for profit, whereas Debian has succeeded as a volunteer-based, democratic structure. The project has probably spawned more derivative distributions than any other, and been the heart and soul of non-commercial linux distributors.

2 archetypes (Red Hat and Debian), followed by 2 derivatives (RHEL and Ubuntu). In a way, it shows how well open source software (OSS) enables giants to stand on the shoulders of other giants.

Ubuntu has almost certainly brought in more users (and consequently, added legitimacy) than any other linux distribution. They derived a significant amount of help from Debian, the GNOME project, even Red Hat and others, but the Ubuntu team has still contributed a huge amount, in their words, to fill between the gaps.

In terms of user-friendliness, the Ubuntu distribution has been unmatched for nearly 5 years.

Perhaps a controversial pick here, but while there are a TON of great linux distributions out there, KNOPPIX truly invented the livecd. Nowadays, distributions can hardly be taken seriously without a crucial livecd component.