PCB Design – Connecting Two GND Planes with Vias Standard Practice

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I've been studying the Arduino Uno layout and noticed that there are about 40 vias that connect the GND polygons on the top and bottom. Here's a picture with the vias circled:

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Is this a standard practice? I'm a hobbyist and a novice when it comes to PCB design, but I've never seen this before..

Best Answer

It's called stitching. You want your copper pours (polygons) to be well connected. Any non-connected islands are referred to as "dead copper" and should be removed.

Arduino example is a rather moderate one. On multilayer boards, you can have hundreds of stitching vias.