Everything on the DDonut is donut-shaped, like the verse itself. The people, structures, and landscape are all donut-shaped. Even the most basic components of the DDonut (such as quarks, leptons, and the like) are donut-shaped.
The DDonut is extremely similar to our Earth. It is inhabitated by dohumans and doanimals. These creatures are proprotional to the DDonut's size, and, as such, are absolutely massive. Every person on Earth has a donut version of themselves, which do the exact same things and go through the exact same events as they do.
The hole of the DDonut contains an invisible, extremely large sphere. It contains the smaller verses such as the Bignoseverse. The sphere itself is very hard to penetrate, and entering or exiting it is difficult. It can, however, be done, and many companies offer transport between the inside and outside of the sphere.