Alright kiddo, so imagine a big map of Europe with lots of blue lines running through it. These blue lines show where rivers and canals are located. We call these "waterways".
Now, some of these waterways are used for shipping things like cargo or people, while others are just for fun, like going on a boat trip. Depending on how big the waterway is and what it's used for, we give it a different classification.
Let's start with the smallest classification, which is "Class 0". These are tiny canals that are only used for recreational purposes, like paddling a canoe or taking a leisurely boat ride.
Next up is "Class I". These are also small canals, but they are used for commercial purposes too. That means that boats carrying goods or people can use them to move from place to place.
Moving up again, we have "Class II" waterways, which are larger rivers and canals. Boats on Class II waterways can carry even more cargo and people, and these waterways connect to other larger waterways that cover more ground.
Finally, we have "Class III" waterways, which are the biggest and most important ones. These are major rivers and canals that connect different countries or major cities. They're like the highways of the waterways, carrying large amounts of cargo and people across long distances.
So, there you have it! The different classes of European inland waterways, based on how big they are and what they're used for.