What is the MHC and what are the differences between the two classes?

The MHC is the major histocompatibility complex which are membrane molecules that are present on certain cells. class I is present on all host cells, when these cells get infected they present the antigen on these molecules. class I mostly presents antigens to CD8 T cells. they present intracellular antigens class II is only present on antigen-presenting cells and presents antigens to CD4 T cells. they present extracellular antigens