Third and inches is a phrase used to describe the down and distance on a play. 'Third' refers to the down in the down cycle, of which there are four. 'Inches' refers to the distance remaining until the offense achieves a 1st down. There is no specific measurement for inches, rather it is used if the distance remaining to the 1st down line is less than one yard. If there is more than one yard remaining, inches is not used.
If a team is within 'goal to go' range, meaning that they cannot achieve a 1st down as they are too close to the endzone, inches is not used. 'And goal' is always used after the down in goal to go situations.
Third and inches doesn't occur very often in a Football game. Maybe only a handful of times for a team during the season as well, so there is no fool-proof strategy to possibly the most frustrating down and distance in Football.
Most teams will elect to run the ball right down the middle of the field on third and inches. The only way they can possibly be stopped is if the defensive front has a great push through the offensive line, but it can happen. Sometimes teams run the ball with the quarterback, called a quarterback sneak. Often, the quarterback will take the ball then punch it over the center's head hoping that the ball crosses the 1st down line.
Very rarely will a team pass the ball on third and inches. A passing play usually only occurs if the team is willing to run another play on 4th down if they pass fails. However, passing on third and inches can lead to a big play if the defense is counting on a running play.