a) The entire time between the end of the active picture time of one line and the beginning of the active picture time of the next line. It extends from the start of front porch to the end of the back porch. b) The video synchronizing signal before and after each active television line that defines the border or black area at the left and right side of the display. In a CRT, it hides (blanks out) the electron beam’s retrace path as it returns from the right to the left of the display to begin scanning a new line.