A sign can be found in the front yard of a house in the US. The people living here want to let their dog play outside and ensure it won’t run into the street. So, they hire a company to set up an “invisible fence”, an electric wire buried in the ground around the yard. The dog wears a special collar and when it walks near to the “fence”, the wire will send out a small shock. The dog quickly learns to stay away from the edge of the yard. As it says at the bottom of the sign, the fence will keep your dog “safe” (away from the street) and “at home” (contained inside the yard).