I've understood that KD tree split points using the median while cycling on each axis. I've also understood that at each node traversal, a nearest search must use a sphere to store to nearest neighbor (in case the query point is very close to the split median).
What I don't understand, is why median are always aligned with one point? Does that mean nodes are always storing one point? Does that mean each node can only have one point and 2 childs nodes ?