In 1977, a surprising phenomenon was discovered — introns. These are sequences of DNA, within genes, which have no apparent purpose. The genes containing them were called "split genes." You could think of introns as long commercials, in a language you don't understand, interrupting your favorite television show right in the middle of the action. Introns are rare within prokaryotic cells. They are rare within the nuclear genomes of single-celled eukaryotes. However, within the cells of multicelled animals and plants almost every gene has introns.....
http://www.panspermia.org/introns.htm