As their name suggests, an altar server is one who serves at and around the altar. They serve the priest and deacon in managing the various items needed for the liturgy. They serve the faithful of the Church by allowing the liturgy to be carried out in a worthy and dignified manner, allowing them to more easily enter into the prayer of Christ and His Church. And they serve the Lord by ministering in the sacred rites here on earth in the way that the heavenly courts minister to the Lord enthroned in heaven. An altar server should seek to serve the Lord worthily and well not only when they are vested and ministering during the Mass, but they should also take that desire to serve the Lord and His people with them from the altar and into their families, their classrooms, and the community at large.
"I will go in to the Altar of God - to God who gives joy to my youth." (Psalm 43:4)