These files are Debian packages. The package files associated with Ubuntu have the .deb suffix because of Ubuntu's close relations with the Debian GNU/Linux distribution. You will need administrative privileges to install a .deb file. See Administrative Tasks for more details.
To install a .deb file, double-click on it. If you prefer using the Terminal, enter:
sudo dpkg -i package_file.deb
To uninstall a .deb file, deselect it in your package manager. Or from a Terminal, enter:
sudo dpkg -r package_name
