The microchip? Phone? Computer? The Wheel? All candidates I'm sure you'll agree. I would argue that it is quite simply the box. You can put stuff in a box, surprise people with it's contents, keep things safe.
The daddy of all boxes - the shipping container - first appeared in the 60s and since then has revolutionised global commerce. Now 80% of stuff coming into the UK arrives in a shipping container.
The BBC this week have started a new feature to measure the humble shipping container's impact on the world. They've bought their very own, branded it and fitted it with a GPS tracker. Now thanks to this site you can see where in the world it is. Over the next year they'll report on it and follow it's journey.
Sounds mind numbingly dull doesn't it? Still the more you think about the more amazing it is how stuff is shipped from China factories to our shop shelves all thanks to these containers. Think how many of these containers you pass on lorries as you travel along the motorway - they all have their own destination and are all controlled by someone.