What is the purpose of the color buttons on the remote supplied with the Android TV?

The remote supplied with the Android TV models has four color buttons.

You can only use these buttons within certain menus or within certain apps. If you can use these functions, the menu or app will provide information regarding what function corresponds with the button. The color buttons are not customisable. 

Press the color button that corresponds to the function you want to use.

NOTE: The image below is an example of how the color buttons are used in the Guide menu.