The Presbyterian Church (U.S.A.) has approximately 2.3 million members in over 10,000 congregations which are served by 14,000 ordained and active ministers. Our denomination has its office headquarters in Louisville, Kentucky.
Presbyterians trace their history to the 16th century and the Protestant Reformation. Our heritage and much of what we believe began with John Calvin (1509-1564), whose writings crystallized much of the Reformed thinking that came before him.
The Presbyterian Church (USA) website has some detailed information on Presbyterian beliefs.
Here is a link to that information:
What Presbyterians Believe