Vectors are secondary control points connected to vertices on a spline or patch object. They are also referred to as handles or vector handles.
Kinds of vector handles:
1. Corner
2. Smooth
3. Bezier
4. Bezier corner
Vector handles are visible as small green squares when you select a vertex. However, if the Vectors filter is checked (for a patch object), handles can be selected and transformed without selecting a vertex first. A transform cursor appears when you move onto a vector.
Each vertex in a shape can be one of four types: