The Stearman (Boeing) Model 75 is a biplane which originally saw use as a military trainer. According to Wikipedia, at least 10,620 were built in the United States during the 1930s and 40s.
After WWII, thousands of surplus aircraft were sold off for civilian use. Modified for crop dusting, the Stearman became popular as an agricultural aircraft. They are also sought after as aerobatic planes.
In evocative red, this PT-17 variation was built in 1943. I photographed VH-ILW at Wings Over Illawarra in May, 2019. The aircraft now operates out of Woolongong Airport, NSW, Australia.