In twenty-four years, Debian has gone from one of half a dozen leading distributions to the premier representative of Linux. Its derivatives Linux Mint and Ubuntu are the most popular distributions today, and new security and server distributions are likely to be based on Debian itself.
So far, over three hundred other distributions have been based on Debian -- so many that in recent years Debian has tried to position itself as the upstream project for them.
There are at least seven reasons for this runaway popularity. However, depending on your interests, Debian's features can come at a cost.
Rumors depict Debian as a distribution for hardcore Linux users. That may have been true once, but today Debian has many features that appeal to every level of user.
Early on, Debian gained a reputation for being hard to install that it has never altogether lost. In reality, though, the reverse is true, and Debian has the most thorough-going installer available. Although most people installing Debian only need a shortened version, the Debian Installer allows the selection of almost every detail -- so long, of course, as you are prepared to spend a couple of hours installing.
If you are having trouble getting Debian to run on your hardware, take the example of Ubuntu and use the advanced version of the Debian Installer to solve your problems. Short of Linux from Scratch, you won't find a more customizable installer.
Debian installs with only free software. However, if you choose to work with proprietary software, add
contrib non-free to the end of each line of /etc/apt/sources.list, then run
apt-get update. The contrib section contains free software that requires non-free software to run, while non-free section contains proprietary software. Officially, neither section is tested as thoroughly as the rest of Debian, but unofficially, their stands are still high.
Each Debian release officially supports nine hardware architectures, ranging from amd64 (64 bit Intel) to arm64 and PowerPC. Another five architectures are unofficially supported, while three are unsupported but listed anyway.
In comparison, many distributions, including the popular Linux Mint, support only 32- and 64-bit Intel chips. Others, like Fedora, have dropped support for many architectures that Debian still supports, such as SPARC. If Debian doesn't run on your hardware, the chances are no other distribution does.
The introduction of new technologies like Systemd often causes problems when upgrading to a new release. However, Debian makes a point of creating packages that make the changeover as smooth as an ordinary upgrade.
Probably no one has counted exactly, but Debian includes over 40,000 packages -- and possibly over 50,000. Either number is generally assumed to be larger than any other distribution, even though few other distributions count their own packages.
The only packages that Debian is unlikely to have are recent ones. However, Debian and its derivatives are so common today that if a project bothers to create packages, they probably do in the .deb format.
Debian's three main repositories are Stable, Testing, and Unstable. These repositories are supposed to be organized for the purposes of producing a new release, but it is a rare user who can resist the temptation to raid Testing and Unstable for the most recent software.
Mixing the three repositories can cause problems, especially if you borrow core packages from Testing and Unstable. Yet, looked at another way, their availability lets you choose your priorities. If reliability matters, then stay with Stable. If you want the latest software, enable Testing and Unstable -- but be careful.
All distributions have guidelines for their packages, but the Debian Policy Manual is by far the most comprehensive. The manual details every possible aspect of what a package may contain and how it can interact with other packages, and every package must adhere to it. The result is that the Debian Stable repository is almost certainly the most dependable version of Linux available. Even Unstable is as stable as other distributions most of the time -- although occasionally it can have some unpleasant surprises.
So, if Debian is so wonderful, why does anyone bother with any other distribution? The question has many answers, but these are probably the most common ones:
In Debian, getting non-free software is as easy as adding the repositories. However, for some users, even that is too much effort. They prefer a Debian derivative like Linux Mint or Ubuntu that makes getting non-free drivers or tools like Flash even easier.
While most users have accepted the introduction of Systemd a few years ago, some continue to fault Debian for using it. They see Systemd as too powerful an administration tool, and suspect it as a ploy by Red Hat to control the desktop. The Debian wiki includes instructions for replacing Systemd with Init, but the process is cumberson, so those who object to Systemd often prefer a derivative distribution like Devuan, which installs without Systemd.
The cost of Debian's stability is often software that is several versions behind the latest. This cost becomes especially obvious in the kernel and desktop environment; for example, Debian Stable has yet to include the fourth release series of the kernel or the fifth release series of KDE, despite both being available for a couple of years.
Debian does have Security and StableUpdates repositories to help keep Stable more current, but neither makes Debian cutting edge. Debian is most current immediately after a general or a point release, but even then its software versions are behind most other distributions.
The Debian Inevitability: Although the advantages of Debian outnumber the cons, whether Debian suits you is a matter of your priorities. For networking, Debian is an obvious choice, especially if you prefer to support yourself rather than buy a service contract from Red Hat or SUSE. But, for a desktop user, Debian's frequent lack of up-to-dateness may be frustrating, especially if you have hardware unsupported by its kernel.
Fortunately, if Debian doesn't meet your needs, then one of its derivatives probably will. Even if you don't consciously plan to use a derivative, probability suggests than you will wind up using one anyway. These days, avoiding contact with Debian is nearly impossible.