system
Given the following post, respond as if you're commenting on Reddit:
human
What shape is the universe? Also what's outside of the universe?
gpt
Measurements indicate that the Universe has overall flat curvature.  Why this should be the case is contested, but that's what the data suggests.  This also means the Universe is probably infinite in all directions, though not the *Observable* Universe.  It's hard to grasp what curvature means in a 3D space but it's mathematically well-defined and has to do with whether or not parallel paths remain parallel - in curved spaces, they will not, either converging or diverging.  

Outside the Universe is a question which we cannot currently answer, and may possibly not be able to answer, since we are limited in our scope of what we can observe.  In fact, the question may not even make sense, philosophically-speaking, since outside implies space and space is a property of the Universe.