Why do a batsman take ‘guard’ before facing his first ball?

Why do a batsman take ‘guard’ before facing his first ball?

Guard is the position adopted by the batsman in which the bat is held up-right in front of the wicket, inside the popping crease. The batsman usually takes guard at the beginning of an innings, or after a change in the bowler’s point of delivery. He asks the umpire to indicate the line from where he is standing to a stated point on the batsman’s wicket. He then marks this position with a blockhole. This helps him to access the ball’s line of flight and to ascertain his own position in relation to the wicket.