How To Install .deb Packages Without “Ubuntu Software” in Ubuntu 16.04

Ubuntu 16.04 is the first version to include the new replacement software app, GNOME Software???and it already has a show-stopping bug. Currently, in Ubuntu 16.04, it is not possible to install third-party applications using the Software app. This misstep is only temporary as Canonical is already hard at work on solving the problem. In the meantime though, here are some ways to install those DEB files without the Software app.