What are cnc inserts?

what are the types and grades of Inserts or carbide tips used in Computer Numeric Control (CNC) machines? Specially the inserts used in metal working not wood or plasic. I know CNMG, DNMG, VVNMG, SNMG, but wanna know mre about there grades and styles. like what is a chip breaker and all. im willing to pay some money too for a personal guidance online or in person over the yahoo msngr. u may email me at mr.tandon at gmail - dot - com.