Automatically install a single font

1. Download a TrueType font. (The file extension will be .ttf.) Unzip your file if necessary.

2. Double click on the downloaded file. This should open a font-viewer window.

3. Click Install Font in the lower right-hand corner. Congratulations! Your font has been installed.

The above will not work on all systems as the Font Viewer needs root privilege to install a font. To deal with this:

1. Open a terminal window

2. Type "sudo gnome-font-viewer and hit enter (replace with the path to the font file you want to install!)

3. Enter your user password when prompted

4. Click "Install". Job done!

Manually Install Multiple Fonts

1. Download TrueType fonts. (The file extension will be .ttf.) Unzip your files if necessary.

2. Move your files to the ~/ Directory. The ~/ Directory is your home folder. This means that if you were logged in as cruddpuppet, the directory would be /home/cruddpuppet/ .

3. Go to Applications > Accessories > Terminal. This will take you to the terminal.

4. Type cd /usr/local/share/fonts/truetype without quotes. This is where Ubuntu keeps its fonts. (The path is cd /usr/share/fonts/truetype on some distros)

5. Type sudo mkdir myfonts without quotes. This will make a directory called myfonts in which to store your fonts. If youre not logged in as root, you will be prompted to provide your password.

6. Type cd myfonts without quotes. This moves you into the new directory.

7. Type sudo cp ~/fontname.ttf . without quotes. This moves the TrueType fonts into your new directory. (Alternatively, type sudo cp ~/*.ttf .; the * acts as a wildcard, allowing you to move all your fonts from the ~/ Directory at once.)

8. Type sudo chown root fontname.ttf and then sudo mkfontdir without quotes. Since ownership has to belong to the root, this makes a directory for your font.

9. Type cd .. and then fc-cache without quotes. This lets Ubuntu know that the fonts are installed so that they dont disappear.

Source - here