A consecutive sentence results in a longer sentence than a concurrent sentence. If you imagine two ice cubes, one that will melt in five years and the other in four, under consecutive sentencing the prison officials wait until the five year sentence is completed before counting time off of the four year sentence. In our example the two sentences served consecutively will result in an actual time of nine years minus good time. Sometimes the law requires consecutive sentences such as a new crime that is committed while serving another sentence in prison or jail, firearm enhancements and habitual offender time. Often however the sentencing judge simply wants to impose a greater sentence and decides upon consecutive terms to make the punishment greater.
A concurrent sentence results in a shorter sentence than a consecutive sentence. Using the two ice cubes, they both begin melting at the same time and after four years, the smaller cube has completely melted and the other cube only has one year left to go. So in our example concurrent sentences for five and four years will result in five years of actual time.