Weight-lifting contests have been common since ancient times and were apparently included in the ancient Greek Olympics and were a part of the original Olympic games in 1896. Women's weight-lifting began in the 1980s.
Weights are mounted on a steel "barbell" which weighs 20 kilograms for male competition and 15 for female competition. The weights themselves are rubber-coated steel discs, color-coded for their different weights, and held in place by 2.5 kg collars. Identical weights are placed at each end of the barbell. The barbell has patterns engraved on it to assist the lifters to get a steady grip on the bar. Competitors start with the weighted barbell placed in the middle of a 4 x 4 metre wooden floor, coated with non-slip material.
There are two different weightlifting events - the "snatch", in which competitors must lift the barbell above their head in one steady movement, and the "clean and jerk" where competitors first "clean" the barbell from the floor to an intermediate position. They then squat with the barbell resting on their chests, then stand straight while continuing to rest the barbell, then "jerking" the barbell to a position above their head.
In both cases, for a successful lift, competitors must hold the bar steady above their heads, with arms and legs straight and motionless. Three judges judge the successful completion of the lift. Once a competitor has met the requirements in their opinion, each judge shines a white light. When at least two white lights are shown, the lift is regarded as successful and the competitor may drop the bar. If the competitor fails to achieve a successful lift in the opinion of a judge, a red light is shown. The lift must also be achieved within a time limit or it does not count.