Gerber Viewers are great for viewing your PCB manufacturing files. Each file is assigned a color (like:Green, Red, Yellow, and Blue) and then hundreds of lines, circles, and various shapes are displayed onto the screen. This is perfectly fine for CAM experts, but have you ever wanted to see "exactly" what your final PCB looked like before it was manufactured.
This tutorial demonstrate how to perform a realistic PCB Preview, View Nets, and checkout Panel NC RoutsTabs.
Movie Tutorial: https://vimeo.com/160926034