The MAA American Mathematics Competitions has 3 levels 

American Mathematics Competition 8 (AMC 8):  

AMC’s middle school level competition* 

American Mathematics Competition 10/12 (AMC 10/12):  

AMC’s high school level competition* 

American Invitational Mathematics Examination (AIME):  

AMC’s invitational competition for high scoring AMC 10/12 participants