A direct shot is a blot that is six pips or less away from an opposing checker. The number needed to hit the blot can show on either die, or as a combination of both dice.
In this example, red has a direct shot, needing a three to hit the white checker on the twenty-one point. 6-3, 5-3, 4-3, 3-3, 3-2 and 3-1 all hit, as well as 2-1 and 1-1.
When the number needed to hit a blot is seven or more pips away, it is called an indirect shot. A specific combination of both dice is required to hit.
In this example, white's blot is eight pips in front of red's pieces on the twenty-four point. Only a combination of both of dice can hit the blot: 6-2, 4-4 and 2-2. 5-3 does not hit because neither the five or three can be played legally from the twenty-four point.
A direct shot is much more likely to be hit than an indirect shot. In general, avoid leaving pieces exposed needlessly, and if you need to leave a piece exposed, leave an indirect shot in preference to a direct shot. You will be hit less often.
Basic Backgammon Strategy - Indirect and Direct Shots