Baptisteries were originally created when the church moved the ceremony of baptism from large, outdoor bodies of water to the inside of religious facilities. Baptisteries can be large enough for two people to occupy the space while one of the occupants is completely submerged, or baptism can be done in front of a baptismal font, which is a smaller, more portable furnishing, usually used for baptising babies.
Portable baptisteries are also available. They can be erected and disassembled as needed. They do not need to be designed as part of the church, although a space for this activity should be carefully thought out in the design phase.
Most christian churches consider baptism an important part of the church and the Christian Life.