Breps. Nearly all commercial cad packages operate on boundary representations of objects.

Mesh is also a boundary representation. I think you meam NURBS.

	▲	MITSardine 2 hours ago \| parent [-]
		It's just the name, BREP stands for Boundary REPresentation.

bob1029 18 hours ago | parent | prev [-]

I would start with CSG if you are new to these ideas: