Shot put originated as "stone put" in ancient Scotland, and was originally contested with stones rather than the metal balls used today. The Olympics included a men's shot put competition in 1896, by which point the modern shot put ball was somewhat standardized; women's shot put did not make it to the Olympics until 1948.
In international shot put competitions, the ball weighs no less than 7.260 kg for men and 4 kg for women, per IAAF guidelines, as of 2010. Until 1927, women's shot put balls often weighed up to 5 kg. At the high school level in the United States, the ball weighs 6 kg for men and 3 kg for women.
Shot put balls are typically made of lead and encased in a steel shell. Shot put balls can be made of solid iron or brass, as well; any metal not softer than brass is an acceptable shot put material. The ball must be spherical in shape and have a smooth surface.