Fractional delay is a delay which is a non-integer multiple of clock. It is particularly used in sampling where you have to adjust the sampling instants by minute delays so that you get more accurate samples. It is also used in FPGAs as (i believe both are almost the same,but these are less than actual clock cycles) tap delays, which correct the skew of some signals to meet setup and hold times.
Fractional delay is a delay which is a non-integer multiple of clock. It is particularly used in sampling where you have to adjust the sampling instants by minute delays so that you get more accurate samples. It is also used in FPGAs as (i believe both are almost the same,but these are less than actual clock cycles) tap delays, which correct the skew of some signals to meet setup and hold times.