Abstract
Microsatellites are highly mutable tandemly repeated sequences that are ubiquitously distributed in bacterial and eukaryotic genomes. Microsatellites became the preferred molecular marker for a variety of applications under the basic assumption that they are selectively neutral. However, the simplicity of this assumption contrasts with the observed variability of mutation rates across microsatellite loci and with the increasing evidence supporting microsatellite functionality. The evolutionary importance of microsatellites is only recently being uncovered with the intense study of their impact on the regulation of gene expression and the interaction among genomic structures.