Arrive at the desk, tag your bag, print your boarding pass, and head through security.

Finally, you make it through.

Get the obligatory super-sized chocolate bar in duty-free and then time to find the gate.

Board the plane and get ready for take-off.

That's all there is to it.

It's all very familiar, but behind the scenes, there's a hidden world of complexity.

Take your suitcase.

Once you've checked in, your baggage sets out on its own, long and secret journey before eventually joining you on board.

Here in Dubai, they handle enormous volumes of luggage.

In just three hours during the morning rush, they process around 50,000 bags.

Stacked like this, they'd reach as high as Dubai's Burj Khalifa, the tallest building in the world.

Annually, the airport handles a staggering 57 million items. That's equivalent to 1,100 Burj Khalifas.

And it's all got to be whisked through the airport.

Every bag must get to the right plane at exactly the right time.

To make sure that happens, each individual bag needs one of these: the humble bag tag.

So on your baggage tag, which we've all seen obviously, you've got things like your name.

And then here we've got the DXB, which is a three-digit code for the airport that you're heading to.

But the really important thing is this mysterious 10-digit number along the bottom.

This is like your bag's passport number, if you like.

So the digits identify the airline, your particular bag's ID number, and then there's a special message digit which identifies the priority of the bag or any other information they need to know.

High priority, low priority, that kind of thing.

This code is part of the universal language of aviation, an international system that knows no borders.

And it determines exactly what will happen to your suitcase after check-in.

25 meters beneath the airport lies a bizarre subterranean world, a sprawling 85-mile high-speed railway network.

Costing around £500 million to build, this is the world's biggest luggage system.

This place is absolutely enormous.

Everywhere you go, there are just miles and miles of these conveyor belts, of these trays that carry the suitcases moving along.

It's really weird.

It's like some kind of post-apocalyptic fairground ride.

But the strange thing is, you don't see any human beings.

It's completely automated.

It's like the robots have taken over. After check-in, your bag is spat onto a yellow tray.

Each tray has been chipped with a unique ID, and a computer tracks which bag has landed in which tray.

So each tray is specific for each bag? - It is, yeah.

So instead of tracking that bag, we track the tray. - You track the tray instead, I see.

That tray has an ID which allows us to track it 100%.

The human being tasked with keeping an eye over this vast system is baggage manager Graham Pollock.

What we have around various points in the baggage system are what you see here are some read stations.

This thing here? - This thing here.

This sensor will pick up the information from the tray.

So the tray knows where it's going, it will tell this part of the baggage system, and here I am, please send me to this location, and then the baggage system will then divert it to the necessary open point.

The computerized brain of the luggage system plots every inch of your bag's journey to the aircraft.

If your flight's leaving within an hour, the computer sends your baggage straight to the loading area.

But for those of us with better timekeeping, our bags end up here, the early baggage storage system.

If you've checked in a little bit too early, what happens is the bags will wait here, and then as soon as it's time for them to make the journey to the aircraft,

a little red robot shuttle will whizz along here, pick up the tray and put it on the conveyor belt system, and then away it goes.

Look, there goes a robot.

The sheer volume of baggage moving through here is breathtaking.

It simply can't be allowed to fail, so it's monitored constantly from the control room.

There are more people working here than on the entire length of the conveyor system.

Copy the double 86, and 374, you need to clear it fast, please.

If it's taking time, let me know, please.

Can you just explain a little bit about how this works?

Because it looks like a full-on, something you might find in a railway network.

It looks incredibly complicated.

Basically, you can see right now, red, yellow, and green.

Green shows the system is normal, basically, the green color.

So red shows a fault.

And there's also yellow as well, so what is yellow? - Yellow is basically a queuing, where the bags wait.

So it's basically like a traffic light.

Green, good, yellow, I might have a problem.

Red is like, "Argh!"