Manifold

A manifold is “a set in which we understand how different numbers in the set are connected to each other…”

Spacetime is a manifold of events and it is endowed with a metric.

A metric is some kind of mathematical object that gives us a notion of distance.

Appendix A

“A manifold is a continuous space of points.”

We love this and changed it to the following:

A manifold is a set of points that creates a continuous space.