In the celebration of the Eucharist, bread and wine become the Body and Blood of Jesus Christ through the power of the Holy Spirit and the instrumentality of the priest. The whole Christ is truly present -- body, blood, soul, and divinity -- under the appearances of bread and wine, the glorified Christ who rose from the dead. This is what the Church means when she speaks of the "Real Presence" of Christ in the Eucharist.
In Matthew 28:20, Jesus tells us “I will be with you always.” This is certainly true in the Eucharist and one of the reasons why many Catholics pray in Adoration.
The practice of Adoration dates back to the early Church but surged in popularity during the Middle Ages. It remains an important part of the prayer life of millions of Catholics.
The USCCB considers adoration “the natural consequence of the Eucharistic celebration.”
For Eucharistic Adoration, the Eucharist is sometimes displayed in a monstrance, a metal stand that resembles a sunburst that holds a consecrated host. Other times, it is kept in a ciborium (the dish from which hosts are distributed during Holy Communion) inside of a tabernacle. A candle signals the presence of Jesus.
Either way, that concept is the same: Being physically present with Jesus, who is physically present with us in the Eucharist.
Churches that offer perpetual Adoration often have volunteers sign up for one-hour time slots so that someone is always present to adore Jesus.