Normally some of the consecrated bread is reserved after Mass in the Tabernacle, and commonly referred to as the Blessed Sacrament. This allows for the distribution of the Sacrament to the ill and others not able to attend Mass. A Sanctuary light alerts us to the presence of the Blessed Sacrament in the Tabernacle. The Tabernacle marks in a particular way the presence of Christ in the parish. Many parishes have a separate Blessed Sacrament chapel, providing an opportunity for private prayer.
At times, the Blessed Sacrament is brought out of the Tabernacle and exposed for public veneration. Or it may be carried in solemn procession, including outside the church to mark a particular celebration such as Corpus Christi.
We genuflect or bow when entering the Church, before taking a seat—as well as whenever we cross before the Tabernacle. We greet others in the entry way to the church but are generally silent or speak softly within the church (nave) as a sign of respect for the Blessed Sacrament.