
For Debian 9.x + MATE Desktop 1.16.x:

Just copy MS Sans Serif.ttf in /home/YOURUSERNAME/.fonts/

Then open a terminal and type:

sudo fc-cache -fv

Close the terminal.
Done.

NOTE: For other distros (Ubuntu, Linux Mint, etc.) and Desktops Environments (GNOME, KDE, etc), check their installation on internet.
