Hi there!

The concept of prayer in Buddhism is somewhat different to that found in the Abrahamic faiths(Judaism, Christianity, and Islam).  I am certainly not an expert, but as I understand it, in these faiths one's prayers are directed to God, with the purpose of prayer varying from faith to faith and from individual to individual; prayers could take the form of petitions-for the essentials of life, or for the forgiveness of sins, for example-or thanksgiving, etc.

In Buddhism, prayers are, generally speaking, affirmations.  There are, however, many praises and petitions to enlightened beings.  In Theravada, the form of Buddhism with which I am less familiar, the Buddha (Shakyamuni or Gotama Buddha) is generally the only deity figure.  Mahayana Buddhism (which includes Zen, Pure Land, and Tibetan Buddhism, among others) there is a greater tendency to invoke other enlightened deities.  (Tibetan Buddhism is the school in which I am most versed so if I say something from here on in that does not jive with somebody else's experience, please add.) 

In Tibetan Buddhism, prayers are considered an essential part of practice; they help set your motivation(which is the most important aspect of all your actions), and prepare your mind for the main practice (meditation, for example.  In fact, prayer can be quite like a type of meditation).  After the main practice, you reaffirm your motivation and dedicate the merit(also known as virtue and positive potential, among other terms) towards the enlightenment of all sentient beings.  Only then is the practice considered complete.  The same pattern is used for teachings; the giving of Dharma teachings should always be preceded by a formal request on the part of the students, which takes the form of ritual, including prayers and the symbolic offering of the mandala.  After the teaching, the merit is dedicated.   The pattern could also be expanded to contain one's entire day; one prays in the morning and dedicates the merit of all one's actions at night, making everything one does Dharma practice. 

As for the form of prayers, there are many traditional prayers which are quite common, such as the seven limb prayer. The great thing about them is that they often contain the entire practice of the path to enlightenment, so not only are you setting your motivation but you're also meditating on the path. 

So I hope this information helps you.  If you would like links to sites with far more extensive info on the subject, let me know and I'll pass them along.

LozangK
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