Topness is a term used in physics to describe how a particle interacts with other particles. Imagine you have a bunch of marbles, and some of the marbles are heavier than the others. These heavier marbles are like the top quark, which is one of the smallest particles in the universe that we know of.
When top quarks interact with other particles, they are like really heavy marbles that push other lighter particles around or pull them closer. Scientists study these interactions to understand how particles work together to create everything around us.
Top quarks are important because they are one of the fundamental building blocks of matter. Just like how different sizes and shapes of Legos can be put together to make different structures, different particles can be put together to make different things in the universe, including us! Studying topness helps scientists learn more about the universe and how it works.