Hi , u are bit confused as i was when i started studying COM . COM & DLL ========= DLL is simply an extension for library component,which are ofcourse COM components ,yes dlls are COM DIFFRENCE ========= u may say dll are subset of COM (although this relation is no good u can't compare them ) COM is a technology ,Dll is just an extension to a library file ,which is made using COM standard USE OF MTS ========== MTS handles/is used for following -Transaction control -maintainance -administration -security -Extensibility -Scalability -Resource pooling & making an application in Tiers , u would know many other uses , as u gain experience ;) Hope u get smater by reading the above regards P.S. PATWAL