Starting in the bass, the two lowest strings are tuned to perfect fifths, C to G and G to D, respectively. Next is a perfect fourth from D back to G, and then the common anomaly of open tunings, the perfect second from G to A. We finish off with another perfect fourth, from A to D. These intervals allow for fairly accessible chord shapes and scales that don't require too much jumping around.
The following image shows common chord shapes in Low C tuning.
And a few movable shapes for major chords:
And some other quandaries:
I've made two sets of scale charts here, the first is from "standard" position, or starting with the root on the fifth string, as one might do for Open G or Open A. The second has the root in the "bass," or starting on the sixth string. This gives an array of scale options for this versatile tuning.