(Horizontal Blanking, Horizontal Blanking Retrace) The process of bringing the electron beam in a CRT back to the left side of the screen after a left to right line has been traced on the screen. The beam is shut off, blanked, during the period of retrace. About 83% of the total horizontal line time is spent writing the line. The remaining 17% is spent bringing the beam back to the left side; retrace, before starting the next line.