Short answers, pulled from the story.
John Wesley had his evangelical conversion at a Moravian service in Aldersgate on the 24th of May 1738, where he felt his heart "strangely warmed" and recorded an assurance that Christ had taken away his sins. The yearly anniversary of this experience is celebrated by Methodists as Aldersgate Day.
Methodism teaches that entire sanctification, also called Christian perfection, is a second work of grace in which original sin is removed and the believer is empowered to serve God wholly. John Wesley described it as "pure love; love expelling sin, and governing both the heart and life of a child of God" and called it "the grand depositum" of the Methodist faith.
The formal break accelerated in 1784 when John Wesley, responding to a shortage of ordained priests in the American colonies after the Revolutionary War, ordained preachers himself to administer the sacraments. The Church of England held that only bishops could perform ordinations, so Wesley's action precipitated the split between American Methodists and the established Church.
Methodism has about 50 million adherents worldwide, and the great majority belong to denominations affiliated with the World Methodist Council, an international association of 80 Methodist, Wesleyan, and related denominations representing about 80 million people. Methodism is declining in Great Britain and North America but growing rapidly in places such as South Korea.
Wesley followed the Arminian position, teaching that salvation was available to all people through free will, while Whitefield held the Calvinist view that God predestined an elect number of people to salvation. This difference strained their friendship and led to a division within early Methodism between Arminian and Calvinistic Methodists.
Charles Wesley, born in 1707, was a co-founder of the movement alongside his brother John and was instrumental in writing much of the hymnody of Methodism. Enthusiastic congregational singing became a primary vehicle for spreading Wesleyan theology, with the hymns expressing Methodism's emphasis on salvation for all, social holiness, and personal commitment.