Retrotransposon are jumping genes (i.e. genes that are not always found in the same place on a chromosome) that have a similar lifestyle to viruses like HIV (the AIDS virus). This means that their DNA is copied into an RNA molecule (just like a regular gene) and the information in the RNA is used to make proteins….
These proteins take the RNA and turn it back into DNA and insert it back into the chromosome somewhere else – its a bit like copying and pasting words in an essay. The big difference between retrotransposons and retroviruses like HIV is that retrotransposons always stay inside our cells and are not infectious – we all have half a million copies of the type I work on, do they have been very busy already!