In Fusion, you can use the Sketch tools to create the sketch profiles that drive the shape of solid, surface, and T-Spline bodies in your design. Sketches are the underlying geometry that support the creation of 3D solid, surface, and T-Spline bodies in your design.
Sketches are often the foundation from which you create solid, surface, and T-Spline bodies in your design, often within the context of an assembly. You can learn more about the different types of 3D and assembly modeling here: