The winding order of meshes in Unity is clockwise.

Winding order produces the face normal, the direction a face is looking. The order of the triangle's indices that look up into the vertices array define the winding order. When viewed head-on, the front face's indices should be ordered in a clockwise fashion.

Triangle indices are expressed as integer values that point to the vertex attribute arrays, and are in groups of three. Vertices can be reused by the triangle indices.