Marston Mat is a special kind of material made out of metal that is used to make long, sturdy roads that can support big, heavy airplanes. Imagine building a road out of big, flat puzzle pieces that snap together to make a strong surface for airplanes to land on.
It's kind of like building with Lego blocks, but instead of plastic, the blocks are made out of metal. Because it's made out of metal, Marston Mat is very strong and durable, which means it can support the weight of massive airplanes without breaking or cracking.
So, when people need to make a temporary runway for planes to land on, they use Marston Mat to create a safe and sturdy surface. This material was essential in many wars, where it was used to quickly build runways for planes to take off and land on in remote areas where there were no airports or other options available.