How to install popular proprietary software in Ubuntu

Ubuntu is committed to Free software (free in cost and free in licensing restrictions), but in "the real world," most computer users are used to having proprietary or nonfree codecs and support software installed (to use Java, MP3s, Microsoft fonts, etc.), so Ubuntu has included, as of Ubuntu 7.04, an easy way to install these nonfree items. The free in the word nonfree refers to licensing restrictions, not to cost.

Go to Applications and select Add/Remove

Under Show, select All available applications

In the Search box, type restricted and the Ubuntu restricted extras package should appear.

If you haven't already enabled extra software repositories, when you check the box next to Ubuntu restricted extras, you'll be asked if you want to enable the installation of unsupported and restricted software. Click Enable.

Wait for the software information to download.

Finally, click Apply Changes to finally install the nonfree software packages.

You'll be asked to confirm that you want to install Ubuntu restricted extras. Click Apply to confirm the installation.

Wait for Ubuntu to download and install the necessary files.

That's it!

You can find more details here (without all the screenshots).

There are also variations on Ubuntu that include proprietary/nonfree software in the default installation. One popular variation is called Linux Mint.