A "faraday cage" is any enclosure that blocks electromagnetic radiation. This includes cellular wireless, WiFi, Bluetooth and RFID signals.
Some people are concerned about the health effects of close proximity to smartphones, which emit strong wireless signals and might be harmful when kept in pants pockets every day for years.
Others worry about wireless hacking, which can include the ability for crooks to hack into your car's key fob and start your car in the driveway, the theft of credit card information from your wallet or wireless hacking of your phone or laptop.
And still others worry about location tracking, whereby your wireless carrier can sell real-time access to your location to many companies.
Another common problem for nomads is that while abroad, you often pay by the megabyte for any data that's downloaded over the cell network while you're between free WiFi hotspots. This can include Google Photos backing up your giant videos, or even security updates pushed down by the OS company.
And I've discovered that on many WiFi networks, the quality of the signal is conspicuously related to the number of devices connected to the network. People can struggled on slow networks with their laptop, without realizing that their unused phone and tablet are slowing the network just by remaining connected.
A company called Silent Pocket solves all these problems with zero effort on your part. They specialize in laptop bags, wallets, purses, smartphone cases, dry bags and other products that function as "faraday cages" -- wireless signals can't get in or out of these accessories. No radiation, hacking, tracking, unwanted data costs or unwanted network access.