Formerly, only young men, whom the Church sometimes hoped to recruit for the priesthood, and seminarians could serve at the altar, and thus altar boy was the usual term until Canon 230 was changed with the promulgation of the Code of Canon Law in 1983 which provided the option for local ordinaries to permit females to serve at the altar. The term altar server is now widely used and accepted due to this. The entire diocese of Lincoln, Nebraska as well as many individual parishes throughout the country retain the former practice, as do traditionalist Catholic orders (FSSP, Institute of Christ the King, SSPX).
An acolyte is one of the instituted orders which is installed by a Bishop. The title of acolyte is still only given to men as it is historically a minor order. This term is now usually reserved for the ministry that all who are to be promoted to the diaconate, whether permanent or transitory, must receive at least six months beforehand (Canon 1035 of the Code of Canon Law).