Opsonization is a process in which proteins like antibodies and complement proteins called opsonins bind to the antigens and get it recognized by the phagocyted which destroys the antigen.
Especially when bacteria is having external capsule than it becomes difficult for phagocytes to attach to the capsular surface as the recognition molecule like membrane carbohydrate of antigen is concealed by capsule.
So to encounter this, antibodies like IgG and complement proteins like C3b attaches to the antigen and get it recognized and opsonized by the phagocytes like macrophages. This opsonization causes the destruction of antigen by enzymatic lysis.
