Three major strength sports are Olympic lifting, powerlifting, and strongman.
Olympic Lifting or O-lifting, properly known as Weightlifting, sometimes abbreviated OL, is the weight lifting sport you see during the Summer Olympics. The competitive lifts are the Snatch and the Clean and Jerk. The Snatch consists of taking a bar from the floor in front of the lifter to overhead, and then standing up with the weight, all in a smooth motion. The Clean and Jerk involves two motions - first "cleaning" the weight to the shoulders in one motion, and then "jerking" the weight overhead. Both the snatch and the clean and jerk involve a significant amount of technique.
O-Lifting is commonly done with "bumper plates" - solid rubber or iron-cored rubber plates, all of uniform size regardless of weight. These allow for the bar to be dropped with less damage to the platform.
In the past, a third lift, the Clean and Press, was also included. But it was dropped after the 1972 games, for reasons that seem to include both increased difficulty of judging proper form and to reduce the length of competitions.
Powerlifting or PL involves three lifts - the squat, the bench press, and the deadlift. The event is scored by adding the maximum completed lift from each of the three, for a competitor's total. Various organizations exist, each with their own rules. "Raw" powerlifting involves little or no equipment (beyond the barbells, chalk, and a belt) while "equipped" lifting involves specialized squat suits, knee wraps, bench press shirts, and other gear designed to improve the maximum lift of the competitor. Ironically, while it is called "powerlifting" the lifts are all very dependent on maximal strength; O-lifting calls for more power (the ability to move a sub-maximal weight fast).
Strongman combines aspects of both OL and PL with its own unique events. Competitors demonstrate their strength, strength-endurance, and power lifting odd objects (barrels, round stones called Atlas Stones, etc.), dragging trucks, flipping tires or cars, walking with heavy weights (the Farmer's Walk), pressing logs overhead, and similar activities. A related sport, The Highland Games, are based on traditional Scottish sports and include more throwing events.