The alignment in a 5-3 defensive front consists of 5 defensive linemen, 3 linebackers, and 3 defensive backs. There are 3 defensive tackles with 2 defensive ends that usually line up wide of the offensive tackles. The 3 linebackers usually line up inside of the defensive ends with one high safety behind them and the 2 corners out wide on the wide receivers. The 5-3 front allows for many options in terms of blitzing the quarterback along with stopping the running game with relative ease.
Having 8 players close to the line of scrimmage allows for success in stopping the run. With 5 down defensive linemen, it creates holes for the linebackers to go and stop the running back more easily than with only 4 or 3 linemen in front of them. Blitzing becomes very easy in this front as well because each defensive linemen is 1-on-1 with an offensive linemen in front of him allowing linebackers to fly through gaps to sack the quarterback. By packing the box, a 5-3 front can stop any sort of power running game that is tossed in its direction.
Because there are 8 players in the tackle box, a good passing game can be really difficult to stop in a 5-3 defense. A strong passing game that attacks the flats and seams can stretch a 5-3 into situations that they cannot defend with consistent success. If an offense decides to stack one side of the field, a 5-3 does not have the versatility to easily adjust and counter that while maintaining good defensive balance. 5-3 is prevalent among youth football because it minimizes the disadvantages as few youth teams are able to have great passing attacks which maximizes the strengths of this alignment in stopping the run close to the line of scrimmage.