Does the Universe expand by stretching or creating space?

The evidence that the Universe is expanding is overwhelming. But how? By stretching the existing space, or by creating new space itself?

The farther away we look in the Universe, the greater the amount that light, gravitational waves, and all signals are lengthened and dilated (or “redshifted”) by the expansion of space.

This effect applies to all observations of objects beyond our own Local Group, but how, exactly, does space itself actually expand: by stretching, or by the creation of new space in the “gaps” opened up by cosmic expansion?

The surprising answer is that both interpretations have their usefulness, but both analogies are fundamentally limited and will fail if you use them incorrectly. The expansion of the Universe is real, but no one analogy is perfect.