The best boxers learn to hit their opponents while standing in front, to the left, or to the right of them. This is known as using angles. You'll see these boxers step to the side, usually at a 30 to 45 degree angle toward the opponent, and punch or punch while they are moving.
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An example would be if you threw a double jab, then stepped at a 35 degree angle toward your opponent and threw a combination of punches. By stepping, you were able to create an opening for your punches AND it makes retaliation by your opponent difficult.