Confirmation is one of the three sacraments of initiation. The sacrament of confirmation is typically conferred at the Cathedral, with the bishop of the diocese.
When we are baptized, we receive – partially – the gifts of the Holy Spirit. Confirmation completes those gifts in us. With Confirmation, we are “sealed” in the Spirit.
When one is confirmed, the bishop will lay hands on the person, and then anoint them with chrism (blessed oil) reserved for just this purpose. The use of oil has a rich history in the Church: it symbolizes (in part) cleansing, healing and strengthening. In Confirmation, we are strengthened in Christ and in our ability to live an outward Christian life.