Lemme venture into some light math, fluff math, that has relevance to physics.
Most of us think of space in the traditional sense, i.e. 3d. Or x,y,z coordinate system. This usual notion of space is called Euclidean geometry, where we have such right angled coordinate system ( x axis and y axis make a right angle, x and z axes make a right angle, etc.). We've held this notion for a long time until a couple hundred years ago when we started to fool around with the math and got some non-Euclidean geometry. So what the heck does that mean?
Well, first think of our surface/space as a simple plane, just a coordinate system involving x,y axes. And your normal sense of what a triangle on that space is the normal triangle you think of. But now suppose that, that your space is the surface on a sphere. Now what would a "triangle" on that surface look like?
The purple is the traditional triangle we think of in the x,y surface. But the black traced triangle is what a triangle on a spherical surface looks like. The sides are curved. The whole surface of the triangle is curved.
So what use is this? Well considering how our earth is a sphere, sort of, wouldn't it be better to develop some non-Euclidean geometry to work with rather than try to convert everything to our traditional Euclidean space? And we do in fact. Physics does it all the time.
If I asked you what what the shortest distance between two points is, you'd naturally say a straight line. However if I asked you in relation to the Earth and your limited travel means, what's the shortest distance between two places on Earth? The answer isn't a straight line, it's a curved line. Airplanes never travel in a straight line from point A to Point B. They travel a curved path.
In physics, the notion of spacetime involves non-Euclidean geometry. These non-Euclidean geometries are some of the hardest things to learn because it doesn't fit into our normal intuitions that we think of, like the standard 3d notion of things. In fact, they don't even really teach spacetime mechanics at the undergraduate level because it requires a very high level of maturity in maths cause of how lacking our intuition is. Anyways, just wanted to share.
Quick challenge: Say there is a plane in the North pole and you want to get to some place close to the equator, say somewhere in the Carribean. Would you just travel a curved path straight down, down as in relation to the picture above? The answer's obviously no, but lemme know if you figure out why.