To keep the center of each character’s baseline parallel to the path’s tangent, choose Rainbow. This is the default setting.
To keep characters’ vertical edges perfectly vertical regardless of the path shape, while letting characters’ horizontal edges follow the path, choose Skew. The resulting horizontal distortion is useful for text that appears to follow waves or go around a cylinder, as on a beverage can label.
To keep characters’ horizontal edges perfectly horizontal regardless of the path shape, while keeping each character’s vertical edge perpendicular to the path, choose 3D Ribbon.
To keep the left edge of each character’s baseline on the path without rotating any characters, choose Stair Step.
To keep the center of each character’s baseline on the path while keeping each vertical edge in line with the path’s center point, choose Gravity. You can control this option’s perspective effect by adjusting the arc of the text’s path.