The word Puritan comes from ‘purity’ or ‘purify’. These were extreme Protestants who wanted to purify the Church of England by returning to the simple and uncomplicated worship and way of life of the earliest Christians.
Many Puritans had fled abroad when Mary I, a Catholic, was queen and had become influenced by Calvinist ideas. When Elizabeth, a protestant, came to the throne these 'exiles' began to return.
Elizabeth’s Religious Settlement meant that the country was now officially Protestant, but allowed some traditions of Catholic worship. At first, many Puritans seemed to accept the Settlement, but they soon started organising campaigns to make it more Protestant.