A saint (from Latin, sanctus) is one who is holy, that is, set apart for God's service. It is a person who has cooperated with God's grace to the extent that his or her holiness is beyond doubt.
Saints in the Bible
In the Holy Scripture, the word saint is used to refer to those who have been set apart for the service of God, consecrated for his purposes. As such, all members of the Church are called saints, regardless of their personal holiness or sinlessness. It is still appropriate to use the term in this way.
Saints in the Church
Aside from the more general use of the word saint to refer to all members of the Church, Holy Tradition also ascribes Saint as a title to particular persons whose lives have shown most clearly what it means to follow Jesus Christ. These saints are popularly glorified (canonized) by the Church, often in the modern era with a formal service to recognize and affirm the veneration of them by the faithful.
Saints are not thought of as either perfect or infallible, and it is only because of the work of Christ in them that the Church praises these people. It is because we see our Lord's countenance reflected most clearly in their faces that we publicly laud them, ask them to pray for us, and encourage one another to follow their examples.
Recognition of saints
The people of the church do not create saints, they recognize as saints those whom God himself has glorified, seeing in their lives true love for God and their neighbors.
From the beginning, the Church recognized the righteous ancestors of Christ, forefathers, as grace-filled men and women whose lives were pleasing to God. Also the prophets who predicted Christ's coming and the apostles and evangelists who proclaimed the Gospel were assumed to be saints.
Next the martyrs and confessors who risked their lives and shed their blood in witness to Christ were also recognized as saints.
In time, ascetics who followed Christ through self denial, were numbered among the saints.
Bishops and priests who fought against heresy and proclaimed the true faith are recognized by the Church as saints.
Today, holy people, in all walks of life, can be recognized as saints.