Phone GPS

One nice thing (or bad thing depending on your feeling about spying) is Waze monitors your travels and uses them. For example it knows when there is a traffic jam because everybody running Waze is having their speed reported back to the system that tracks everybody and can show traffic slow downs. Other GPS apps do the same, but they are relying on speed sensors on the freeways and they aren't as accurate. I think Google maps does the same as it shows traffic backups in red even on surface streets where there are no speed sensors so it has to be getting it's info from people running the app. I've found Waze to be more accurate. Sometimes Google maps shows a backup even long after it has cleared.