Powerlifting is a strength sport that consists of three attempts at maximal weight on three lifts: squat, bench press, and deadlift.  These movements are great for developing and benchmarking strength, and you’ll find them in almost every sport’s strength & conditioning regiments.
The sport is not exclusive to the largest and strongest men; there are many weight categories for each gender and age, and for most, the real competition is with themselves.
In Ontario, the governing body is Ontario Powerlifting. Nationally, there are several prominent organizations:
Internationally, the governing body for Powerlifting at the World Games is the International Powerlifting Federation. They’ve made a great introduction video for the sport which you can see below: