Jehovah's Witnesses are a religious movement whose members base their lives and beliefs on the early Christian church and the Bible.
The movement grew out of Bible studies groups set up by Charles Taze Russell in the 1870s.
The name Jehovah's Witnesses was adopted in 1931 to reflect the growth of the organisation's missionary work - with every member expected to visit non-believers to try to convert them. There are more than 6 million Witnesses worldwide and about 125,000 in the UK. Famous members include Prince and 1960s' Pools winner Viv Nicholson.
Followers believe that the Bible is divinely inspired and historically accurate and have produced their own translations that reflect this.
They dispute several of the main tenets of mainstream Christianity. For example, they reject the idea of that God is a trinity of father, son and Holy Spirit. Instead, they believe that God is a single being called Jehovah. They believe Jesus is a lesser and separate being, while the Holy Spirit is regarded as the force of God.
Followers also believe in the imminence of Armageddon, or the "End Times", which they believe started in 1914. In 1966 the movement said the world would probably come to an end in 1975, and when it did not there was a temporary decline in membership.
When the end finally does come, they believe only 144,000 people - known as the anointed - will go to heaven and rule Earth with Christ from there. The rest of the Jehovah's Witnesses will spend eternity in paradise on Earth.
Partly because of their belief that the Bible is the word of God, Jehovah's Witnesses are not supposed to undergo blood transfusions, even with their own, stored blood. This belief stems from four passages in the Bible, which command people not to eat blood.
More recently the Witnesses have cited research into the safety of blood transfusions to back up their position. Their official website suggests that blood transfusions increase the risk of developing cancer and cannot be adequately screened for the presence of HIV.
Willingly accepting a blood transfusion is regarded as sinful and followers who do so risk being shunned. Being given a transfusion against your wishes is not regarded as a sin. Similarly, children who are transfused against their parents' wishes are not made outcasts.
Guidelines drawn up by the Association of Anaesthetists in 1999 state that to not respect Witnesses' rejection of transfusions would be "unlawful, ethically unacceptable and morally wrong" - even if this meant the death of the patient concerned.
The Jehovah's Witnesses amended their rules on blood transfusions in 2002. The church no longer takes action against a follower who willingly undergoes a blood transfusion, but the individual will no longer be considered one of the faithful. However, they can rejoin the church if they repent.
In the 1980s, Jehovah's Witnesses set up a hospital liaison committee to help understanding between patients of the faith and the medical staff who treat them.
Bloodless surgery - where blood loss is minimised by operating in stages or using drugs - is increasingly being used in the UK, after being pioneered in the US. Jehovah's Witness church groups also raise money to buy machines that recycle a patient's own blood.
As the Witnesses note on their website, several countries - including the UK - respect the right of adult members to refuse transfusions. However, when it comes to children, doctors have been more willing to go to court to have medical responsibility transferred from the parents.
