The official founder was Charles Taze Russell (1852-1916), At the age of seventeen he became engaged in discussion with someone who denied the existence of hell. Then, at eighteen, he wandered into a church where the Second Coming of Christ was being discussed and became interested in the subject. He tried to work out just when Christ would return, and published his findings in a tract entitled The Object and Manner of the Lord's Return. He placed the date as 1874, later revised to 1914. This return was to be spiritual rather than physical [In other words, He'd come, but no-one would see Him! - Ed].
In 1874 Russell became pastor of a Bible class, and from 1879 began to publish a magazine: Zion's Watchtower and Herald of Christ's Presence. The movement expanded and by 1880 there were thirty new congregations in seven states. The movement became officially chartered in 1884.
Russell was accused of fraud by the Brooklyn Daily Eagle and lost the subsequent law-suit. In 1879 he married, and appointed his wife secretary- treasurer of the society, but later left both the society and her husband. June 1912 saw Russell denounced in a pamphlet by Rev J J Ross, a Baptist minister. Russell sued again, and was found to have lied on several points.
The movement was taken over by Joseph Franklin Rutherford on Russell's death, and the society grew rapidly. Conscientious objection resulted in imprisonment for him and many followers in 1918, but they were eventually released on pressure from the Witnesses (note that today Witnesses claim not to follow the teachings of Russell).
There is no such place as hell, that is contrary to the idea that God is love. But instead, there is a terror of not meeting Jehovah's standards for salvation. Hence the massive emphasis on witnessing door to door. They are earning their salvation - salvation is not by faith alone. Furthermore, Jesus is not divine (the concept of the Trinity is rejected) but is a created being like all others [They get this from their understanding of Colossians 1:15 - Ed]. His resurrection was not physical, but spiritual. Initially known as the angel Michael, He was stripped of His angelic nature when He came to earth, where He became just another man.
Much of the teaching of the Jehovah's Witnesses is tied up in their eschatalogical beliefs (see below). Apart from the elect 144 000, the rest (the 'other sheep' or 'Jonadabs') must earn their salvation. Armageddon (initially forecast for 1975 (probably early Autumn)) is to be a world-wide thermonuclear devastation. On one side the world, lead by the Christians, who are of the devil, and all the heathen. On the other side the 144 000 and the 'other sheep'. There will also be a battle between God and Satan. Over two billion will die. Only faithful Witnesses will survive. Then great people like Moses, David, etc. will be resurrected, swiftly followed by the 'other sheep', and all those who never had a chance to hear. They will have a chance to accept or reject Jehovah at the end of the millennium.
Man faces four possible destinies.
Source: adaptation of diagram in Ridenour 1967:138, upon which this article is based