Why does Ubuntu provide the Multiverse repository?

Solution 1:

The distinction between restricted and multiverse is that Ubuntu itself pledges to support the software in restricted, whereas software in multiverse is provided by Ubuntu but with no guarantee of Ubuntu support. I's not really fair to say universe and multiverse software is "unsupported", just that support will be dependent on the third party that produced it, or other third parties, and/or the "Ubuntu community": volunteers that package software for Ubuntu. This is opposed to software in main and restricted where Ubuntu have allocated dedicated people to ensure its support.

The distinction between restricted/multiverse and main/universe is that the software in restricted/multiverse is not fully free by Ubuntu's definition of free software, though it is still free enough for Ubuntu to distribute it in a repository. Usually this means that it contains binary code for which the source is not available, though sometimes it can be other licensing issues.

So, technically, multiverse contains software that:

• Ubuntu can distribute, but is not fully free - probably contains binary code without source.
• Ubuntu itself doesn't guarantee to support.

What are examples of packages in multiverse?

Chiefly, ubuntu-restricted-extras is a metapackage containing a suite of software Ubuntu thinks you really are likely to want, even though it's not open source software.

• Installer for Adobe's Flash plug-in

• Microsoft Core Fonts for the Web

• A selection of video or audio codecs with non-free licenses

• Unrar

Other packages in multiverse, but not part of ubuntu-restricted-extras, include a small range of Linux based software included either because Ubuntu thinks you're very likely to want to install it on Ubuntu, or because it is very much open source software in spirit but misses out on qualifying with Ubuntu's definition of free software for some reason, such as by including some binary code without source, or some license terms that make its license incompatible (eg a non-commercial clause, or any other "custom" clauses added to otherwise compatible open source licenses).

Solution 2:

Your needed answer is quoted from http://www.howtogeek.com/194247/whats-the-difference-between-main-restricted-universe-and-multiverse-on-ubuntu/

Multiverse – Unsupported, Closed-Source and Patent-Encumbered Software

Multiverse is the place for questionable, controversial stuff. This includes closed-source software like the Adobe Flash plug-in and packages that depend on closed-source software, like plug-ins for Skype. It also includes open-source software with legal restrictions — for example, audio and video playback software that infringes patents. DVD playback software isn’t included here — there are serious legal issues around the open-source libdvdcss DVD playback library. In fact, libdvdcss appears to be illegal in the USA.

Ubuntu can’t officially distribute these packages along with the main distribution, but they’re provided here for your convenience. On other Linux distributions, the stuff here is often found in third-party repositories you have to go out of your way to find — RPM Fusion for Fedora, Packman for openSUSE, and Penguin Liberation Front (PLF) for the defunct Mandriva distribution.

As with the Universe repository, Multiverse is a community-supported repository. There’s no guarantee of security updates here. Because so many of the packages are closed-source, the community often couldn’t fix problems you encounter even if they wanted to.

You can spot these packages by their “Unknown” license. As with Universe, the Ubuntu Software Center states the Ubuntu community may provide updates, but Canonical won’t.

Indeed I find to word to add to the above, great explanation and detailed what is needed