The zebra analysis tool projects stripes onto a surface so that you can inspect the continuity between surfaces.
Surface continuity is a measure of how smoothly two surfaces flow into each other. A car hood, for example, can be composed of multiple small surfaces that appear to be one because of the smoothness of the surface continuity. Zebra analysis can also identify flaws in what should be a fair surface in a ship hull, an issue that can increase drag and have structural consequences in some cases.
In the seam where two surfaces meet, the way that the zebra stripes align and curve tells you a lot about the smoothness of the join.
The stripes line up, but they do not veer away from each other at sharp curves (because they share the same curvature). This distinction is subtle and a little harder to discern from G1 continuity.