It is generally accepted among all Quakers that the founder of their religion was a man named George Fox in 17th century England. Fox began to preach what he believed was true Christianity, and when he found groups of others that shared his same beliefs, they travelled together and called themselves Friends or the Religious Society of Friends. The name Quaker came from a blasphemy, but for one reason or another, it stuck. According to Wikipedia citing Chapter 4 of George Fox’s journal, Justice Bennet of Derby “called us Quakers because we bid them tremble at the word of God.”
To give one definition of Quakers today and what they believe would be impossible. Many groups have broken apart and stemmed off from the original group, but they still have the Quaker name. For example, different groups across the United States have yearly meetings, and at those they produce an output that explains what each group believes. Beliefs can range from very conservative and Christian to very liberal and either Universalist or Christian Universalist beliefs.
Common throughout Quakerism is the belief in continued revelation from God to man. Along with this belief, Quakers also believe that all humans have the ability to communicate directly with God without the help of clergy members.
Silent worship or “unprogrammed” meetings are not like “programmed” services that are led by a pastor. Instead, Quakers believe that they are better able to enter into the worship of God without instruction; praying or speaking aloud as the Spirit leads them.
Quakers also typically do not practice traditional sacraments of the Christian faith. For example, baptism by water is a common practice among almost all Christian groups. However, Quakers believe that an inward baptism of the Holy Spirit is sufficient, and an outward representation is not needed.
Especially amongst the more evangelical groups or Christian Universalist groups of Quakerism, there is the belief that scripture comes secondary to God. They believe that Jesus Christ is the word of God, not the Bible. They believe in the Bible and that the scriptures are holy, but if a man receives a revelation from God that contradicts the Bible, the newer revelation is correct.
Another interesting and common practice among Quakers is their way of making business decisions. Instead of having a meeting to discuss business, they will host a worship service focused on seeking God for their business. And instead of voting, a decision is only made when members feel there is a consensus about which direction is the right one to go in.