THE EPISCOPAL CHURCH is the American branch of the Anglican Communion (The church of England).
After the American revolution, Anglicans living in the United States quickly changed their name to "Episcopalians" in order to avoid persecution and also to sever ties with England who was seen as the enemy. We are, however, still part of the worldwide Anglican Communion.
The full legal name of the national church corporate body is the "Domestic and Foreign Missionary Society of the Protestant Episcopal Church in the United States of America", which was incorporated by the legislature of New York and established in 1821. The membership of the corporation "shall be considered as comprehending all persons who are members of the Church". This, however, should not be confused with the name of the church itself, as it is a distinct body relating to church governance.
The Anglican Communion is an inheritor of 2,000 years of catholic and apostolic tradition dating from Christ himself. It is rooted in the Church of England. (Note that "catholic" is spelled here with a small "C", meaning "universal and including a wide variety". Episcopalians are not associated with Roman Catholicism or the Church of Rome except as common followers of Jesus' teachings)
The Episcopal Church came into existence as an independent denomination after the American Revolution. Many of the founders of the United States of America were active Episcopalians. The National Cathedral in Washington DC is an Episcopal church. Today we have between two and three million members in the United States, Mexico, and Central America, all under the jurisdiction of our Presiding Bishop, Michael Curry.
We have many "firsts" for a protestant faith tradition:
In 1988 the Diocese of Massachusetts elected the first Anglican woman bishop, Barbara Harris.
In 2003, at St. Paul's Church in Concord, the Episcopal Church elected the first openly gay bishop, Gene Robinson.
When the Church of England spread throughout the British Empire, sister churches sprang up. These churches, while autonomous in their governance, are bound together by tradition, Scripture, and the inheritance they have received from the Church of England.
Together they make up the Anglican Communion, a body headed spiritually by the Archbishop of Canterbury and having some 80 million members, making it the second largest Christian body in the Western world.