HOW does iPhones and other newer forms of technology adjust to Daylight Savings Time?

So today was DST, time to change our clocks, but I already knew for a long time, that advanced forms of electronics like most smart phones and modern computers would automatically adjust, and I wonder, how? I searched online and could only find questions like "will my iPhone adjust to DST?", or "all my schedule was delayed by an hour, why?" These are questions that I feel for people who never paid any attention to their devices before.

Some articles I read suggested that connectivity to networks such as the Internet will notify the device and that turning on Airplane Mode may prevent the automatic adjustment. Some articles I read asks questions like "Will my phone adjust to DST?" That got an answer like "yes, my wife's and my phone did. We use T-Mobil". Why is phone carriers involved? Without being able to have service, how does iPods and some iPads still adjust? What about offline computers? They all seem to do fine.

What I'm interested in is HOW? How does these devices know when to change and which direction to change? What are the processes that goes on to make the change happen?

DST is programmed into the device when it is made…

Any kind of computer these days will automatically update its time setting by connecting to "time servers" over the Internet.

This means that, for most modern computers, they will automatically adjust themselves for the correct time, based on your geographical time zone…

Many websites on the Internet work the same way (such as http://onlineclock.net, which basically shows you a web-based clock using your computer's own time settings).