Jehovah's Witnesses are a fundamentalist Christian denomination best known for door-to-door evangelism, distribution of religious literature such as The Watchtower magazines, and their refusal to accept blood transfusions.
The religion report over 7,000,000 members worldwide, and over 18,000,000 attendees at their annual Memorial ceremony.  Census data, pew surveys, and statistical abstracts, which rely on self-identification of religious membership, estimate the number of Jehovah's Witnesses to be 30-60% higher than reported, as the religion's own report limits membership to those who actively participate in evangelism.
Jehovah's Witnesses believe that blood is a sacred representation of life and that God forbids its use for purposes other than atonement for sin (sacrifice). They have thus forbidden their followers from eating meat from which the blood has not been drained, food products containing blood, and from receiving blood transfusions, regardless of its medical necessity and of the consequences to their life or health.
Specifically, they are directly forbidden from willingly accepting a transfusion of stored whole blood, red blood cells, white blood cells, platelets, and plasma, on penalty of excommunication and the threat of God's disfavor. Preoperative extraction followed by postoperative re-transfusion of their own blood is also disallowed, though certain intraoperative re-transfusion procedures (such as salvage) are allowed. Organ and bone marrow transplants are discouraged as well, though the final decision is left to the individual. Those choosing to follow discouraged actions are often informally ostracized.
They are directed to follow their own personal conscience in deciding to use other components of blood, or other products derived from or produced in blood (such as antivenins).
One of the controversial aspects of their refusal to accept blood transfusions is in that, against the advice of their doctors and surgeons, they often hold their critically ill minor children to the same rule, who are themselves not mature enough to decide to follow the belief willfully.
It is difficult to assess actual membership among Jehovah's Witnesses, as their organizing body reports neither officiated members nor church attendance. Instead, they report:
- The peak number of members who submit a report on their evangelism efforts, tabulated monthly.
- Combined attendance at their annual memorial ceremony.
- Combined peak attendance at their annual three-day convention.
The latter two do not reflect membership, as attendance of both includes casual and one-time visitors. Ministry campaigns are carried out for a few weeks before the event in an attempt to invite as many new people as possible.
The first is not an exact representation of actual membership, as it excludes those who attend services, consider themselves members, but who do not participate in evangelism efforts. It excludes even officiated members who do not evangelize. But given that better information is not reported, it may be considered the best representation available.
In reporting religious affiliation, governments and third-parties usually rely on self-identification. This results in the inclusion of children and others not recognized as members by the church. But as they are collected the same way regardless of religion, these reports may be considered accurate when comparing one religion to another.
The practice of excommunication, known among Witnesses as "disfellowshipping" and to some as "shunning", is used as punishment for breaking the tenets of the religion.
Members are prohibited from speaking to excommunicated members of the church, even when the outcast person is a member of their immediate family. Speaking regularly to an excommunicated person is itself a basis for excommunication, though more often (especially in the case of family) the penalty is exclusion from holding leadership positions and from some church activities.
Some exceptions are allowed where regularly speaking with the excommunicated person is required for other reasons, such as between married couples, for the care of minor children, child visitation and financial support, and for shared financial ventures and businesses.
Though an exception is made for existing business ties, the church discourages continuing such ties except as required by law.
During the early 20th Century Jehovah’s Witnesses saw black people as inferior. Black people it was believed had the curse of Ham in their hearts and were fit to be servants. Black people could get spiritual benefits by staying meek and accepting their inferior status. Black people were not encouraged to feel good about being black, rather they should hope to become white. As a special blessing black Jehovah’s Witnesses might become white through God’s intervention. Black people were uneducated and therefore would not benefit from the tracts and reading material supplied to white congregations.
Prejudice is much less evident in the 21st Century though few Black people have reached the highest administrative levels of the Watchtower. There are suspicions that Hispanics are today considered too uneducated to benefit from intellectual reading material. 
Controversies About Jehovah's Witnesses
A cult is popularly defined as an individual or organization which employs intensive methods to control behavior, thinking, and emotions of its followers. Included in these methods are isolating the group from standard social interaction and limiting the information available to the group.
While this can apply to many religious groups to some degree, it is not commonly applied to call a religion a cult unless the behavioral control results in harm to the members.
An example of this type of behavioral control within the Jehovah's Witness religion is requiring members isolate themselves from social interactions outside the religion, and then excommunicating ones who do not follow their tenets. The harm caused by this isolation is in that subsequent excommunication causes an almost total collapse of that person's social support structure.
Another example of harm is in their policy forbidding blood transfusions, and their limiting and misrepresenting information about them. This policy has often resulted in the death of the member or a member's child who refused to have (or was prevented from having) a transfusion.
Due to these methods of control being employed and the result sometimes being harm to the members, some consider the Jehovah's Witness religion to be a cult. The Ex-Cult Resource Center considers the Jehovah's Witnesses a cult and has material on them.
However, what a celebration consists of is not explicitly defined by the Jehovah's Witness organization. Some members do celebrate their or their kids' birthday surreptitiously in some deniable or explicable way.
These beliefs are coupled with their belief that birthday celebrations are idolatrous anyway, so they do not celebrate Christmas and generally consider it one of the more abhorrent holidays.