The Catholic Church has declared many men and women to be "saints", honoring them with that title before their name. The word "saint" means "holy one". In the Bible, the term is used to refer to all Christians (Eph. 1:1). Actually, the "communion of saints" includes the faithful on Earth (the church militant), in heaven (the church triumphant), and in purgatory (the church suffering) (CCC 954). Nowadays, the term "saint" is usually used to refer to the select group of Catholic Christians who are in heaven, honored with the title of "saint", by being "canonized" (CCC 828), or by having long been venerated as saints for their martyrdom or their excellence in Christian virtue. In the beginning, the martyrs received the title of "saint", but when the Roman persecutions ended, and martyrdoms were less frequent, the term began to be used in reference to other holy men and women.
In the Catholic Church, these "saints" have been honored since the beginning of the Christian era. Why do we honor the saints? We honor the saints because they were model Christians and practiced great virtue while on Earth, just as we honor any person when he excels at one endeavor or another. We also honor the saints because in doing so, we honor God, just as an artist is honored when his artwork is praised.
In what ways is this honor given by Christians? For one, we honor the saints by imitating their virtues (CCC 2030). It is said that "imitation is the highest form of honor." It is not always possible to imitate all the actions of the saints (ie. their austere penances), so we must imitate the virtues that produced those actions. We imitate the saints because in doing so, we imitate Christ. As St. Paul says, "Imitate me, as I imitate Christ" (1 Cor. 11:!).
We also honor the saints by respecting their relics (what they left behind––bones and possessions) and images. We venerate their relics because their bodies were temples of the Holy Spirit (1 Cor. 6:19), and because God uses them do work miracles, such as the bones of Elisha, which brought a dead man back to life (2 Kgs. 13:21; Acts 5:15, 19:12).
We also honor the saints through their images (CCC 1161). (Actually, Catholics do not "venerate" the images, they venerate the saint represented by the image. All signs of veneration shown to the image (kissing, kneeling, praying before) is directed to and received by the saint represented by the image. We respect the images of the saints and use them for veneration to honor them, just as we do with pictures and photographs of our loved ones. Images are not idols, the latter being statues that were worshiped as gods, the former being reminders of saints to aid us in prayer and devotion (CCC 212).
Another way in which we honor the saints is by invoking them (CCC 956). By "praying to the saints" (actually, "asking them for their prayers"), we show our respect for their intercessory powers, humbly and confidently placing our trust in them. God allows the saints to hear our invocations. The saints respond by praying on our behalf, just as Christians on Earth ask others to pray for them, and in turn pray for others.
Although not "saints" in the common usage of the word, angels are also "holy ones". Angels are spirit beings (CCC 329) who lack a body, and have great intelligence and a free will (CCC 311). They also have great wisdom, power, and holiness. Angels act as God's messengers, pray for men, and guard them (CCC 332, 334): "For God commands the angels to guard you in all your ways. With their hands they shall support you, lest you strike your foot against a stone" (Ps. 91:11-12). Every man on earth has his own "guardian angel" (CCC 336): "See that you do not despise one of these little ones; for I tell you that in heaven their angels always behold the face of my Father who is in heaven" (Matt. 18:10; Acts 12:15). It is traditionally believed that all angels belong in one of nine choirs–Seraphim, Cherubim, Thrones, Dominions, Virtues, Powers, Principalities, Archangels, and Angels. Besides these angels, who reside in heaven and serve God, there are also the fallen angels–the demons (CCC 391), who were tested by God, rebelled against him (CCC 392), and were cast out of heaven and into hell: "War broke out in heaven. Michael and his angels fought against the dragon, who fought back with his angels, but the dragon was defeated, and he and his angels were not allowed to stay in heaven any longer. The dragon was thrown out; that ancient serpent, named the devil, or Satan, that deceived the whole world. He was thrown down to earth, and all his angels with him" (Rev. 12:7-9). Satan tries to harm God's children. The main way he does this is by tempting us to sin (CCC 1520).
To honor the saints, Catholics read the lives of the saints, and meditate on and imitate their virtues. They hang or place images of the saints around their home or place of work. Finally, they ask the saints often for their prayers. This can be done by invoking a different saint every day for a certain intention––praying to the saint whose feast day is celebrated that day. Catholics also make use of patron saints––saints that have been designated by the Church as special intercessors for a given intention or location. Catholics can also "adopt" a saint and make him his personal patron.