The high jump is a track and field event in which competitors must jump unaided over a horizontal bar placed at measured heights without dislodging it. In its modern most practised format, a bar is placed between two standards with a crash mat for landing. In the modern era, athletes run towards the bar and use the Fosbury Flop method of jumping, leaping head first with their back to the bar. Performed since ancient times, competitors have introduced increasingly more effective techniques to arrive at the current form. The approach of the high jump may actually be more important than the take-off. If a high jumper runs with bad timing or without enough aggression, clearing a high bar becomes more of a challenge. The approach requires a certain shape or curve, the right amount of speed, and the correct number of strides. The approach angle is also critical for optimal height.