Can you explain this war driving thing for the average person?
"War Driving" became popular back when Wifi was starting to get popular.
Basically, you would literally drive around with something like a Laptop with a GPS and some WiFi device that as you drove it would record gps locations, SSID (network names), Mac addresses for the SSIDs (so even if you change the name, the device is still tracked and now you know its new name) as well as time and security settings for the network.
The "modern" version is basically that all cell phones also use SSID's along with GPS and other GeoIP tricks for glandular location data. Because of the data captured you can get a good idea of where someone/something is based on the SSIDs/Mac Addresses near the device. You can even use these inside large buildings for basic "gps like" navigation and tracking.
War Driving is a "modern" version of "War Dialing". That was a whole different thing and was back in the earlier days of the (dial up) internet. You basically would use something that would have the modem in your computer auto-call phone numbers and recording information on that number. Stuff like - Did it pick up, Did it seem like a computer/fax machine, Was it not connected... etc...etc...
Thanks, I don't really understand the purpose of it other than it being a hobby. What nefarious things can one accomplish with this sort of information?
Well, it used to be "easier" to do "bad stuff". Wifi "security" was a fucking joke for a decade+. I could crack your key's in less than 5 minutes as long as I could capture some data. Now, I am on your internal network and can do about anything I want. Including using your house as a proxy to commit other crime.
It's not nearly as easy these days but sometimes things come up and there is a major exploit like that.
Google/apple/etc mostly use it to spy on you (and help governments and companies spy on you).