Many fonts are packaged for Ubuntu and available via the "Fonts" category of the Ubuntu Software Center. If you prefer apt-get, search for packages starting with otf- or ttf-.

Font files that are placed in the hidden .fonts directory of your home folder will automatically be available (but /etc/fonts/fonts.conf indicates it will be removed soon.). You can also place them in the ~/.local/share/fonts directory on newer versions of Ubuntu per the comments below.

You can also double-click on the font file (or select Open with Font Viewer in the right-click menu). Then click the Install Font button.

If you need the fonts to be available system-wide, you'll need to copy them to /usr/local/share/fonts and reboot (or manually rebuild the font cache with fc-cache -f -v).

You can confirm they are installed correctly by running fc-list | grep "<name-of-font>"

You may need to restart some programs, like OpenOffice Writer, before they actually show the new fonts (usually such programs are caching the font list when they start up).

Edit: Changed advice to manually install into /usr/local/share/fonts instead of /usr/share/fonts to reflect comments and best practice.

Copy the fonts to /usr/local/share/fonts or a subfolder (such as /usr/local/share/fonts/TTF) and then run sudo fc-cache -fv. There are some graphical programs you can install to make this easier, but I've never felt the need to try any of them. The Ubuntu wiki page on Fonts here may be of help too.

GIMP will find them in there then.

Installation of fonts from 3rd party websites is almost too easy. Download and save the file somewhere to your computer:

Then double click the font to load the font interface:

Select the Install Font button located at the bottom right of the screen.

You don't have to install as root. Create a folder called .fonts in your home directory (if you don't already have one), drop the font file in there, run Gimp, job done.

(You may have to enable Edit->Preferences->Views->Show hidden and backup files in Nautilus to be able to see .fonts and other ‘hidden’ folders in your home, if you haven't already.)

If you install font(s) in folder .fonts in your home directory (another directory $HOME/.local/share/fonts in ubuntu 18.04 is ok) , you may need to run fc-cache -rv (not sudo) in order to cache fonts in your home directory as well.

Font Manager

Application for Install and Manage fonts.

Can install Multiple Fonts.

To install fonts Click on Manage Fonts Button and select Install Fonts Option.

Font Manager can be installed from apps.ubuntu.com or and with Software Centre. If with commandline ;

sudo apt-get install font-manager

Installing font is just copying its file to specific directory.

There can be different directories on different systems. For example at my system they are:

• /usr/share/fonts/ — fonts for all users
• ~/.local/share/fonts/ — fonts for particular user

There can be any subdirectories you want. It may help you to organize your font collection.

Here is the command to get list of font files that your system uses.

fc-list -f '%{file}\n' | sort

Look at it and you'll get the idea of where fonts are located in your system.

There is also an application called fontmatrix that can help install and manage fonts on Ubuntu. To quote the introduction on the website:

Fontmatrix is a real Linux font manager, available on any platform and as well for KDE (which already had Kfontinstaller) as for Gnome. It's purpose is to recursively query the fonts (ttf, ps & otf) in the directories you give it to search, sort them quickly, (avoiding bugged or broken ones) and show them. Then, you can tag them, sub-tag, re-sort according various tags, preview... Even create a pdf Font Book...

Fontmatrix has been available to install from the Ubuntu universe repository since jaunty, and version 0.6.0+svn20100107-2ubuntu2 is currently in maverick and natty. A brief explanation about using fontmatrix is available on their website.

Also, there are lots of fonts available as software packages. Font packages are named in the form ttf-* or otf-*. It is better to install fonts as packages instead of manually if possible. You can use tools such as Synaptic, apt-get or the Ubuntu Software Centre. The Software Centre has a dedicated fonts section.

In addition to manually installing them inside ~.fonts (see bobince's answer) and FontMatrix (what nhandler shows you), there is also another font manager aptly named Font Manager (install Ubuntu package for 10.10, or download package for 10.04 and maybe older versions) that is quite lightweight (and has a Gtk GUI).