Prayer has a very personal meaning arising from an individual's religious background or spiritual practice. For some, prayer will mean specific sacred words, for others, it may be a more informal talking or listening to God or a higher power.
The word "prayer" comes from the Latin precarius, which means "obtained by begging, to entreat." Prayer is rooted in the belief that there is a power greater than oneself that can influence one's life. It is the act of raising hearts and minds to God or a higher power.
There is no one set way to pray. Forms include spoken prayers, silent prayers, and prayers of the mind, the heart, and union with God. Prayers may be directed (e.g., prayers for specific things) or non-directed, with no specific outcome in mind.
Specific types of prayers include:

Prayer is important in a healthcare context simply because it is used so widely. "Surveys indicate that nearly 90% of patients with serious illness will engage in prayer for the alleviation of their suffering or disease" (Jonas, W. 2003). Among all forms of complementary medicine, prayer is the single most widely-practiced healing modality (Glazer, S. 2005). Prayer is the second most common method of pain management (after oral pain medication), and the most common non-drug method of pain management (Puchalski, C. 2004).
The following explanations have been offered as to how prayer helps improve health:

Several studies correlate prayer with improved health and well being. "Patient spirituality and religiosity have been shown to be correlated with reduced morbidity and mortality, better physical and mental health, healthier lifestyles [5], fewer required health services, improved coping skills, enhanced wellbeing, reduced stress [6]and illness prevention" (McCord, G. 2004). Similarly, it is well documented that hope, belief, and faith positively influence health outcomes (Palmer, R. 2004).
A well-noted study by Dr. Herbert Benson, a cardiovascular medicine specialist at Harvard Medical School, documented the potential healing benefits of spiritual [7] practices, such as prayer and meditation [4] (as well as hypnosis and other relaxation techniques). Benson demonstrated that the body responds to these practices with what he calls the relaxation response, which consists of "a lowering of the heart rate, blood pressure, and breathing rate; a reduced need for oxygen; less carbon dioxide production" (Dossey, L. 1993). In effect, the relaxation response is the opposite of the stress response and can be consciously used to modulate the impact of stress.
Some of the effects of prayer may be due to the larger context within which prayer occurs, which is usually one of religious commitment and social support [8].
The benefits of intercessonary prayer are more controversial. A 2007 review of research on intercessonary prayer concluded that most of the data is equivocal and that "it is not sensible to interpret any of the interesting results with great confidence."
The following issues exist in studying prayer and healing. Some are true of most medical research and some are unique to prayer.
In a healthcare setting, there are several sanctioned roles for a spiritual adviser, including chaplain, ordained clergy, rabbi, priest, minister, and spiritual director. A healthcare practitioner, if experienced and skilled in "listening presence" can also function informally as a spiritual advisor, but it is wisest to refer to an expert if there are any spiritual issues or needs.
Chaplains work on site at the hospital and their role is to attend to the spiritual needs of patients in the hospital. They may come from any religious tradition, and therefore may have a wide variety of training and experiences. Most hospitals today require chaplains to have qualified credentials beyond their specific religious education and/or seminary level education. The standard for this training is usually one to two years of certified Clinical Pastoral Education, endorsed and accredited by The Association for Clinical Pastoral Education, Inc.
Spiritual directors are trained to help support and nurture patients' faith. They may or may not be associated with a particular denomination, but they typically work with patients of all faiths. Spiritual directors are trained to be "listening presences" who help people deepen their faith lives. A spiritual director may work with a patient alongside a chaplain in a hospital and may continue with that patient after they are released from the hospital.
Patients are also welcome to invite their own priest, minister, rabbi, or cleric to address their own spiritual needs.
Online Spiritual Assessments [10]
The Twelve Peace Prayers [11] - this website includes Baha'I, Buddhist, Christian, Hindu, Jainist, Musliim, Native American, Shinto, sikh, and Zoroastrian prayers for peace.
The World Peace Prayer Society [12] is a nonprofit, non-sectarian organization dedicated to spreading the message and prayer "May Peace Prevail on Earth" all over the world.
The World Prayers website [13] gathers the great prayers written by spiritual visionaries into an online database representing all life-affirming traditions. Many of these prayers have been used for hundreds if not thousands of years.
Dossey, L. (1993). Healing Words. San Francisco: Harper Collins Publishers.
Glazer, S. (2005). Can Spirituality Influence Health? CQ Researcher, 15(2).
Jonas, W.B., Crawford, C.C. (2003). Healing Intention and Energy Medicine. New York: Churchill Livingstone.
McCord, G., Gilchrist, V.J., et al. (2004). Discussing Spirituality with Patients: A Rational and Ethical Approach. Annals of Family Medicine, 2.
Palmer, R.F., Katerndahl, D., et al. (2004). A Randomized Trial of the Effects of Remote Intercessory Prayer: Interactions with Personal Beliefs on Problem-Specific Outcomes and Functional Status. The Journal of Alternative and Complementary Medicine, 10(3).
Puchalski, C. (2004). Spirituality in Health: the role of spirituality in critical care. Critical Care Clinics, 20.
Roberts L, Ahmed I, Hall S. (2007). Intercessory prayer for the alleviation of ill health. Cochrane Database Syst Rev. 2007 Jan 24;(1):CD000368.
Links:
[1] http://www.takingcharge.csh.umn.edu/sites/default/files/images/thumbnails/prayer.jpg
[2] http://www.takingcharge.csh.umn.edu/glossary/3#term31
[3] http://www.takingcharge.csh.umn.edu/glossary/3#term24
[4] http://www.takingcharge.csh.umn.edu/explore-healing-practices/meditation
[5] http://www.takingcharge.csh.umn.edu/lifestyle
[6] http://www.takingcharge.csh.umn.edu/create-healthy-lifestyle/stress-mastery
[7] http://www.takingcharge.csh.umn.edu/create-healthy-lifestyle/life-purpose-and-spirituality
[8] http://www.takingcharge.csh.umn.edu/glossary/3#term37
[9] http://www.dukemednews.duke.edu/
[10] http://www.spiritualityhealth.com/newsh/lists/pth_selftest.html
[11] http://www.csle.org/peace_prayers.htm
[12] http://www.worldpeace.org/
[13] http://www.worldprayers.org/
[14] http://www.takingcharge.csh.umn.edu/our-experts/catherine-owens-duncan-mat-spiritual-director
[15] http://www.takingcharge.csh.umn.edu/explore-healing-practices/what-are-mind-body-therapies
[16] http://www.takingcharge.csh.umn.edu/activities/meditation-exercise
[17] http://www.takingcharge.csh.umn.edu/promo-tiles/start-assessment-now-1