The Watch Tower Bible and Tract Society of Pennsylvania is a nonprofit corporation formed in 1884 under the laws of the Commonwealth of Pennsylvania, U.S.A. It is used by Jehovah’s Witnesses to support their worldwide work, which includes publishing Bibles and Bible-based literature.

 According to its charter, the corporation’s purposes are “religious, educational, and charitable,” in particular, to “preach and teach the gospel of God’s Kingdom under Christ Jesus.” Membership in the corporation is by invitation only and is not based on how much a person has donated. The corporation members and directors assist the Governing Body of Jehovah’s Witnesses.

 Besides the Watch Tower Bible and Tract Society of Pennsylvania, Jehovah’s Witnesses use dozens of legal entities in various countries. Some of these entities include in their name such terms as “Watch Tower,” “Watchtower,” or a translation of one of these.

 These various legal entities have enabled us to accomplish much since they were established, such as the following:

•   Writing and publishing. We have published some 220 million Bibles and about 40 billion pieces of Bible-based literature. Our publications are available in over 900 languages. The jw.org website allows people to read the Bible online without cost in more than 160 languages and to get answers to such Bible questions as, “What is the Kingdom of God?”

•   Education. We conduct a variety of schools for Bible instruction. For example, since 1943, some 9,000 of Jehovah’s Witnesses have benefited from the intensive training provided by the Watchtower Bible School of Gilead, enabling them to serve as missionaries or to stabilize and strengthen our worldwide work. And each week, millions of people, including non-Witnesses, receive instruction at meetings conducted in each of our congregations. We also conduct literacy classes and have produced a textbook in 120 languages that teaches people to read and write.

•   Charity. We have provided material relief to those suffering from tragedies​—whether man-made, such as the 1994 genocide in Rwanda, or natural, such as the 2010 earthquake in Haiti.

 Although much has been accomplished through the corporations and legal entities that we use, our work is not dependent on any of them. Each Christian has a personal responsibility to fulfill the God-given mandate to preach and teach the good news. (Matthew 24:14; 28:19, 20) We believe that God is backing our work and that he will continue to be the one who “makes it grow.”—1 Corinthians 3:6, 7.