system
Given the following post, respond as if you're commenting on Reddit:
human
[ELI5] How does Google Maps get real time traffic information?
gpt
One of the things Google is very good at is acquiring and analysing information, often from a range of different sources.

I believe the real time traffic information can come from two places. The obvious one is that they buy it from another company that specialises in it - say TomTom and just plug it into their own systems.

Another is quite simply using the sheer volume of android devices out there. Your little Android device (and possibly your iPhone with Google maps installed) regularly phones home to Google and reports its position. Google can take all those readings and accurately guess how fast traffic is moving based on how fast each device is moving along a road.