Sawdust is what's left over when you cut or saw things like wood. It's like tiny pieces of wood that are very small and look like dust, almost like a powder. When people work with wood, they often produce a lot of sawdust. That's because it's easier to cut wood into different shapes and sizes if you use special machines that create sawdust.
Sawdust can be used for lots of different things. Sometimes people use it to make things like particleboard or other building materials. Other times, people will use it as a form of insulation or to help absorb spilled liquids. Some people even use sawdust to create a softer surface on playgrounds or in pet enclosures.
While sawdust might look like a big mess, it's actually very useful and can be recycled into lots of different things. So, just because it looks like dust, doesn't mean it's not important!