In many Christian denominations, an acolyte is anyone who performs ceremonial duties such as lighting altar candles. In other Christian Churches, the term is more specifically used for one who wishes to attain clergyhood.
The functions of an acolyte or taper-bearer are therefore carried out by readers, subdeacons, or by non-tonsured men or boys who are sometimes called "acolytes" informally. Also, the term "altar-boys" is often used to refer to young altar servers. Subdeacons wear their normal vestments consisting of the sticharion and crossed orarion; readers and servers traditionally wear the sticharion alone.
In recent times, however, in many of the North American Greek Orthodox Churches, for the sake of uniformity, readers have been permitted to wear the orarion (The Bishop presents the reader, who is to serve on the altar, with the orarion). Readers do not cross the orarion while wearing it, the uncrossed orarion being intended to slightly distinguish a reader from a subdeacon.
In the Russian tradition, readers wear only the sticharion, and do not wear the orarion unless they have been specially blessed to by their bishop. (This might be done if a reader must occasionally serve in the role of a subdeacon, or for some other reason the bishop believes is fitting.) If a server has not been tonsured, he must remove the sticharion before he can receive Holy Communion.
In the early church, a taper-bearer was not permitted to enter the sanctuary, only a subdeacon or above was allowed to go in. Nowadays, however, servers are permitted to go in, but they are not permitted either to touch the Holy Table or the Table of Oblation.
An acolyte can assist in worship by carrying a processional cross, lighting candles, holding the Gospel book, holding candles or "torches", assisting a deacon or priest set up and clean up at the altar, swing incense or carry the incense boat, hand the offering plates to ushers, and many other tasks as seen fit by the priest or acolyte warden.
The acolytes wear robes that differentiate them from the clergy, the lay Eucharistic ministers, or the choir, although they may appear quite similarly dressed. These robes can be called albs, cassocks, cottas or a combination of those items. The robe belt worn by many is called a cincture, and frequently reflects the color of the liturgical seasons. It is generally a twisted rope with knots on the ends and is secured around the waist. Wearing crosses or other special pins or symbols is the prerogative of the individual church.
In more traditional dioceses, the acolytes are ranked as they develop their abilities to serve - Trainees, Junior Acolytes, Senior Acolytes and Acolyte of Merit. In others, the functions of acolytes are performed without vestments, and without significant formal training by persons available in the parish.