William Booth was an English Methodist preacher who, along with his wife, Catherine, founded the Salvation Army and became its first General (1878–1912). The Christian movement with a quasi-military structure and government founded in 1865 has spread from London to many parts of the world. It is known for being one of the largest distributors of humanitarian aid.

Open-air preaching, street preaching, or public preaching is the act of evangelizing a religious faith in public places. It is an ancient method of proselytizing a religious or social message and has been used by many cultures and religious traditions, but today it is usually associated with evangelical Protestant Christianity. Supporters of this approach note that both Jesus and many of the Old Testament prophets often preached about God in public places. It is one of the oldest approaches to evangelism.