Repbase Update (RU) is a curated database of repetitive DNA elements found in eukaryotes.
It contains over 3500 entries, each of which consists of a sequence, description and references. RU also contains Repbase Reports, an online journal solely for publications reporting new transposable elements, and Transposon Pub, a visualisation tool. RU is one of the most-used databases for homology-based transposon prediction tools, including RepeatMasker.
Read the following publication for more details:
Jurka, J., Kapitonov, V.V., Pavlicek, A., Klonowski, P., Kohany, O. and Walichiewicz, J., 2005. Repbase Update, a database of eukaryotic repetitive elements. Cytogenetic and genome research, 110(1-4), pp.462-467.