If you are using a mouse, trackball, or touchpad with extra buttons in Windows, chances are the manufacturer has created software to configure the buttons. Rarely do they create such software for Linux. Btnx (button x) can be used to configure the mouse buttons in Linux for a variety of pointing devices.
With a three button mouse, typically people keep the default settings. With a five button mouse, the extra two buttons often go unused. The default is that they typically are used to go back and forward in web browsers and file managers. This