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.
Jehovah's Witnesses claim that, while most churches count their membership by total annual or occasional attendance, they count their membership only by active participation in their ministry. Their membership numbers do not include children too young to participate officially, new members not yet qualified to participate, ex-members, or occasional members who do not submit monthly reports of time spent in the ministry.
While this is perhaps technically true, the statistics made available by the Jehovah's Witness organization are not limited to active membership alone. The statistics emphasized to members of the religion include:
- The number of active Witnesses submitting monthly ministry reports.
- The average number of studies of the Bible being conducted weekly.
- The annual attendance at the observation of the Last Supper.
Notably, the number of Bible studies quoted in the report includes parents formally teaching their children, and the observation of the Last Supper includes anyone who attends.
It is difficult to assess actual worldwide membership of Jehovah's Witnesses, given that none of the statistics provided specify usual or even annual church attendance.
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.
Most holidays are of either religious or political origin, which Witnesses consider idolatrous worship of either a false god or the state, respectively. Thus, Jehovah's Witnesses do not celebrate any secular or religious holidays, save the Last Supper and sometimes wedding anniversaries.
Birthdays are officially viewed as a form of idolatry, and the common American custom (getting really drunk at your friends' expense, which is great) contrary to scriptural principles. The celebration of birthdays is therefore expressly disallowed.
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.
Christmas is considered by Witnesses to be a celebration of mostly pagan origin, observed on a date and in a way that coincides with (and they believe is rooted in) several pagan rituals.
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.
Belief in the pagan origin of Christmas customs and questioning the celebration date is not unique to Jehovah's Witnesses. At least some of the customs thereof are factually pagan [pagan in the sense that they have non-Christian roots], and Christmas as a whole seems to be the evolution of the winter festivals and practices of several cultures and religions. Many post-reformation Christian movements condemn Christmas as an un-Christian holiday.
It is perfectly acceptable for Witnesses to celebrate wedding anniversaries. The idolatrous aspects of admiring and giving gifts to someone on the yearly anniversary of their birth do not apply to admiring and giving gifts to a married couple on the yearly anniversary of their wedding.