According to the Catholic church, a saint is someone who is known for Christian holiness, has shown devotion to God, is exceptionally generous, and is officially honored by the church as one who has attained heavenly glory. A person officially may be named a saint through a complex process called canonization.
To become a saint, a candidate must be named venerable, or a role model of Catholic virtues. The next step is called beatification. In order to be eligible for beatification, a candidate must be responsible for miracles after her death. A candidate who died for her faith is called a martyr, and she may be beatified without having miracles attributed to her.
Once beatified, a candidate is referred to as Blessed. In order to be officially canonized and called saint, the candidate must have an additional miracle attributed to her intercession. An example of this is when someone prays to a candidate for healing and suddenly is cured. Any alleged miracle must be investigated thoroughly by the Vatican.
People of the Catholic faith hold saints in high regard, and they often pray to saints for intercession. They compare praying to saints to asking a friend of God to ask God for a favor.