system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why does 3G use so much battery life on my phone while wifi barely uses any.
gpt
Like you're 5: The phone's wifi is talking to your wifi router, which is in your house. So it can just talk to it without using much energy. But the 3G system is on some telecoms tower that might be miles and miles away, so your phone has to yell really loudly to talk to it, which uses a lot of energy.