Some installations or settings changes require you to restart your computer. In most cases you don't need to actually reboot it, you only need to restart the explorer.exe process.
Collection of fonts on our computer is quite big, but sometimes we want to use some special font. We can find it on web and install it on computer for personal use.
If you leave your computer running on a 24/7 basis you might be interested in determining the amount of uptime that has accumulated since the last reboot.