Abstract
Transposons are DNA sequences capable of moving in genomes. Early evidence showed their accumulation in many species and suggested their continued activity in at least isolated organisms. In the past decade, with the development of various genomic technologies, it has become abundantly clear that ongoing activity is the rule rather than the exception. Active transposons of various classes are observed throughout plants and animals, including humans. They continue to create new insertions, have an enormous variety of structural and functional impact on genes and genomes, and play important roles in genome evolution. Transposon activities have been identified and measured by employing various strategies. Here, we summarize evidence of current transposon activity in various plant and animal genomes.