Wait - on the iPhone, they tell you when a person has read your message?

I don't own an iPhone, never had, might get one in a couple of days… But I was on instagram, and this girl posted a convo with her and her boyfriend, and underneath her message it said "Read 10:15 PM"

So I was just wondering.

Its called imessage. The thing is that it only works between ipod or iphone to eachother. It also tells you when they are typing back.

Yes, iMessage lets you know when someone has read your message and vise versa however you can turn that option off in settings.

It does not mean they read it. If they have a chat open and set their phone down, and the phone is not locked, the next message will pop up and claim it has been read.