ORTHOCENTRE: It's the point of concurrence of altitudes of a triangle

 

CIRCUMCENTRE: It's the point of concurrence of perpendicular bisectors (which are drawn perpenicular from the mid point of the side ) of a triangle

 

MEDIAN: It's the mediator of a side. It is drawn from a vertex to the midpoint of the opposite side . It divides the side into two equal parts

 

INCENTRE: It's the point of concurrence of internal angular bisectors of a triangle

 

ALTITUDE: It's drawn from a vertex to the opposite side perpendicular to it.

                 It cuts the opposite side orthogonally