what is the median,centroid,incentre circumcentre

Median : the point of concurrence of the three medians in a triangle is called it's centroid, denoted by the letter H incentre: the point of concurrence of the three angle bisectors of a triangle is called as it's incentre, denoted by the letter I circumcentre: the point of concurrence of the three perpendicular bisector of a triangle is called as it's circumcentre, denoted by the letter S