"Why do people pray to saints?"

Why do people pray to saints? Do each patron saint have their own prayer? Is it better to pray to saints then to God himself?

-Centerpide

Definition for the word "pray" (according to Dictionary.com)

1. To utter or address a prayer or prayers to God, a god, or another object of worship.
2. To make a fervent request or entreaty.
3. To utter or say a prayer or prayers to; address by prayer.
4. To ask (someone) imploringly; beseech. Now often used elliptically for I pray you to introduce a request or entreaty: Pray be careful.
5. To make a devout or earnest request for: I pray your permission to speak.
6. To move or bring by prayer or entreaty

Based on the definition above, Catholics do pray to the saints to request/implore/beseech the intercession of these people of God but never as worship. "Praying to the saints" come from the the understanding that we are part of the body of Christ (i.e. His Church) and that we pray for one another (James 5:13-18). And saints too are part of the body of Christ, therefore they are also able to pray for us. The only difference is that saints are already united with the Lord (which is a bonus point for those they are praying for; as Scripture says: [the] prayer of a righteous person is effective; James 5:16)! If we know of certain Christian on earth who seem to have special power because of their great faith/holiness, imagine how much more powerful and effective are the prayers of those who are already in heaven!

Let's move on to...

What is a patron saint?
Patron saints are chosen as special protectors or guardians over areas of life. These areas can include occupations, illnesses, churches, countries, causes -- anything that is important to us. The earliest records show that people and churches were named after apostles and martyrs as early as the fourth century. Recently, the popes have named patron saints but patrons can be chosen by other individuals or groups as well. Patron saints are often chosen today because an interest, talent, or event in their lives overlaps with the special area. For example, Francis of Assisi loved nature and so he is patron of ecologists. Francis de Sales was a writer and so he is patron of journalists and writers. Clare of Assisi was named patron of television because one Christmas when she was too ill to leave her bed she saw and heard Christmas Mass -- even though it was taking place miles away. Angels can also be named as patron saints. A patron saint can help us when we follow the example of that saint's life and when we ask for that saint's intercessory prayers to God.

- Catholic Online - Saints & Angels

I am not sure whether each patron saints have prayers of their own but I know well known ones like St. Jude do. :)

Last but not least, please remember that the practice of praying to the saints is just to "supplement" our prayer to God and it can never substitute prayer and worship due only to God Himself. Also do bear in mind that all Christian prayer (whether it's from the Blessed Virigin Mary/saints in heaven/Christians on earth) is directed to God our Father through Jesus Christ His Son who is the "one mediator between God and men" (1 Timothy 2:5)